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  • Articles  (24,297)
  • Articles: DFG German National Licenses  (24,297)
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  • Articles  (24,297)
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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Free Radical Biology and Medicine 10 (1991), S. 177-184 
    ISSN: 0891-5849
    Keywords: Free radicals ; Humans ; Noninvasive analytical techniques ; Oxidative stress status
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Mutation Research DNAging 256 (1991), S. 45-48 
    ISSN: 0921-8734
    Keywords: Ageing ; Humans ; Skin cells ; Telomeres
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 304 (1994), S. 285-294 
    ISSN: 0027-5107
    Keywords: Cotinine ; Genetic monitoring ; Hprt mutation ; Humans ; Lymphocytes ; Pregnancy ; Smoking ; Tobacco
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Mutation Research DNAging 237 (1990), S. 123-130 
    ISSN: 0921-8734
    Keywords: Aging ; Humans ; Ionizing radiation ; Single cell electrophoresis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Peptides 10 (1989), S. 489-492 
    ISSN: 0196-9781
    Keywords: Angiotensin II ; Blood ; Humans ; Radioimmunoassay ; Rats ; [des-Leu^1^0]-angiotensin I
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 6
    ISSN: 0196-9781
    Keywords: Autocrine feedback mechanism ; Cholecystokinin ; Feeding ; Humans ; Radioimmunoassay
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Applied Animal Behaviour Science 39 (1994), S. 141-150 
    ISSN: 0168-1591
    Keywords: Cats ; Foraging ; Humans ; Livestock ; Predators ; Vampire bats
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Applied Animal Behaviour Science 41 (1994), S. 101-114 
    ISSN: 0168-1591
    Keywords: Fear ; Handling ; Humans ; Poultry ; Productivity
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Thermal Biology 5 (1980), S. 249-251 
    ISSN: 0306-4565
    Keywords: Humans ; exercise ; hyperthermia ; oesophageal temperature
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 39-52 
    ISSN: 0308-597X
    Keywords: Ecology ; Fisheries ; Marine resources
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 11
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 43-57 
    ISSN: 0308-597X
    Keywords: Atlantic ; Fisheries ; Management
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 12
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 126-133 
    ISSN: 0308-597X
    Keywords: Fisheries ; Government ; USA
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 13
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 61-62 
    ISSN: 0308-597X
    Keywords: Fisheries ; Marketing ; UK
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 14
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 8 (1984), S. 137-150 
    ISSN: 0308-597X
    Keywords: Fisheries ; International organizations ; Management
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 15
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 7 (1983), S. 197-211 
    ISSN: 0308-597X
    Keywords: Fisheries ; Management ; Property rights
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 16
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 219-235 
    ISSN: 0308-597X
    Keywords: Canada ; Fisheries ; Foreign relations
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 17
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 66-68 
    ISSN: 0308-597X
    Keywords: Fisheries ; Regional government organizations ; West Africa
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 18
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 120-125 
    ISSN: 0308-597X
    Keywords: Exclusive Economic Zones ; Fisheries ; Law of the Sea
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 19
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 27-42 
    ISSN: 0308-597X
    Keywords: Fisheries ; International law ; United Nations Organization
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 20
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 131-139 
    ISSN: 0308-597X
    Keywords: Economic measurements ; Fisheries ; Pacific
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 21
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 7 (1983), S. 267-278 
    ISSN: 0308-597X
    Keywords: Environment ; Fisheries ; Resource management
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 22
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 121-130 
    ISSN: 0308-597X
    Keywords: Atlantic ; Fisheries ; Management
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 23
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 8 (1984), S. 239-258 
    ISSN: 0308-597X
    Keywords: Antarctica ; Fisheries ; Krill
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 24
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 220-236 
    ISSN: 0308-597X
    Keywords: Fisheries ; Resource economics, UK
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Political Science , Law
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Agriculture and human values 17 (2000), S. 125-139 
    ISSN: 1572-8366
    Keywords: Environment ; Fisheries ; Fordism ; Nation-State ; Regulation ; Supranational State ; Transnational corporations ; Transnational State
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This analysis uses an analytical frameworkgrounded in political economy perspectives of theglobalization of the agro-food sector combined with acase study approach focusing on the Marine StewardshipCouncil (MSC) to inform discussions regarding thecharacteristics of societal regulation in thepost-Fordist era. More specifically, this analysisuses the case of the emergence of the MSC toinvestigate propositions regarding the existence of,and location of, nascent forms of a transnationalState. The MSC proposes to regulate the certificationof sustainable fisheries at the global level throughan eco-labeling program. The MSC was created in 1996by the transnational environmental organization theWorld Wildlife Fund and the transnational corporationUnilever. The emergence of the MSC has generatedheated discussion in fisheries management circles thatis in general divided along North/South lines. Thisanalysis indicates that the case of the MSC providesvaluable insights into the possible characteristics ofsupranational regulatory mechanisms that might emulatethe role of the nation-State in the post-Fordist era.
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  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 27 (1988), S. 311-320 
    ISSN: 1432-1432
    Keywords: Genome composition ; Coding sequences ; Isochores ; Humans ; Murids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The compositional distributions of coding sequences and DNA molecules (in the 50-100-kb range) are remarkably narrower in murids (rat and mouse) compared to humans (as well as to all other mammals explored so far). In murids, both distributions begin at higher and end at lower GC values. A comparison of homologous coding sequences from murids and humans revealed that their different compositional distributions are due to differences in GC levels in all three codon positions, particularly of genes located at both ends of the distribution. In turn, these differences are responsible for differences in both codon usage and amino acids. When GC levels at first+second codon positions and third codon positions, respectively, of murid genes are plotted against corresponding GC levels of homologous human genes, linear relationships (with very high correlation coefficients and slopes of about 0.78 and 0.60, respectively) are found. This indicates a conservation of the order of GC levels in homologous genes from humans and murids. (The same comparison for mouse and rat genes indicates a conservation of GC levels of homologous genes.) A similar linear relationship was observed when plotting GC levels of corresponding DNA fractions (as obtained by density gradient centrifugation in the presence of a sequence-specific ligand) from mouse and human. These findings indicate that orderly compositional changes affecting not only coding sequences but also noncoding sequences took place since the divergence of murids. Such directional fixations of mutations point to the existence of selective pressures affecting the genome as a whole.
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  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 35 (1992), S. 7-16 
    ISSN: 1432-1432
    Keywords: Alu source genes ; Humans ; Gorillas ; Retrotransposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A member of the young PV Alu sub-family is detected in chimpanzee DNA showing that the PV subfamily is not specific to human DNA. This particular Alu is absent from the orthologous loci in both human and gorilla DNAs, indicating that PV subfamily members transposed within the chimpanzee lineage following the divergence of chimpanzee from both gorilla and human. These findings and previous reports describing the transpositional activity of other Alu sequences within the human, gorilla, and chimpanzee lineages provide phylogenetic evidence for the existence of multiple Alu source genes. Sequences surrounding this particular Alu resemble known transcriptional control elements associated with RNA polymerase III, suggesting a mechanism by which cis-acting elements might be acquired upon retrotransposition.
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  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 33 (1991), S. 442-449 
    ISSN: 1432-1432
    Keywords: Humans ; Mouse ; Rat ; Codon usage ; Mutation bias ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new statistical test has been developed to detect selection on silent sites. This test compares the codon usage within a gene and thus does not require knowledge of which genes are under the greatest selection, that there exist common trends in codon usage across genes, or that genes have the same mutation pattern. It also controls for mutational biases that might be introduced by the adjacent bases. The test was applied to 62 mammalian sequences, the significant codon usage biases were detected in all three species examined (humans, rats, and mice). However, these biases appear not to be the consequence of selection, but of the first base pair in the codon influencing the mutation pattern at the third position.
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  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 34 (1992), S. 336-344 
    ISSN: 1432-1432
    Keywords: Humans ; Mitochondrial DNA ; Nuclear polymorphisms ; Heteroplasmy ; Genetic differentiation ; Sickle cell ; Rain forest refuges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The identification of genetically coherent populations is essential for understanding human evolution. Among the culturally uniform ethnic groups of west Africa, there are two geographically distinct populations with high frequencies of sickle-cell hemoglobin (HbS). Although the HbS mutation in each group is found on distinguishable chromosomes 11, these populations have been assumed to be parts of a single population. Analysis of mitochondrial DNA (mtDNA) in these populations demonstrated that the two populations identified by alternative chromosomes 11 bearing HbS have distinct distributions of mitochondrial genotypes, i.e., they are maternally separate. These studies also showed that, contrary to expectation, the mtDNA of some individuals is heteroplasmic. For nuclear loci, a comparison of the frequency of alternative alleles established that these populations are genetically distinct. Both the mitochondrial and nuclear data indicate that these populations have been separate for approximately 50,000 years. Although HbS in the two populations is usually attributed to recent, independent mutations, the duration of the separation and the observed geographic distribution of the population allow for the possibility of an ancient origin of HbS. Assuming an ancient mutation and considering the known biogeography, we suggest that HbS protected selected populations from malaria in rain forest refuges during the most recent ice age.
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  • 30
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Peptides 4 (1983), S. 451-455 
    ISSN: 0196-9781
    Keywords: Biliary system ; Cat ; Guinea-pig ; Humans ; Mucosa ; Rabbit ; Radioimmunoassay ; Respiratory system ; Skin ; Substance P ; Sympathetic nervous system ; Urinary system
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 31
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Peptides 1 (1980), S. 55-57 
    ISSN: 0196-9781
    Keywords: ACTH ; Aging ; Attention ; Cognition ; Humans ; MSH ; Peptide ; Visual retention
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 32
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Peptides 5 (1984), S. 319-323 
    ISSN: 0196-9781
    Keywords: Blood flow ; Circulation ; Electromagnetic flowmetry ; Humans ; VIP
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 33
    ISSN: 0165-7992
    Keywords: Cytochrome P-450 ; Dogs ; Humans ; Monkeys ; P-448-H ; Rats
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
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  • 34
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Ethology and Sociobiology 6 (1985), S. 183-187 
    ISSN: 0162-3095
    Keywords: Assortative mating ; Genetic similarity ; Heritability ; Humans ; Kin recognition
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 35
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Ethology and Sociobiology 8 (1987), S. 215-220 
    ISSN: 0162-3095
    Keywords: Humans ; Paternity confidence ; Relatedness
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 36
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 124 (1993), S. 73-77 
    ISSN: 1573-0832
    Keywords: Assessment ; Cancer ; Humans ; Hydrazines ; Mushroom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This assessment focuses on the concentrations of some chemicals present in theAgaricus bisporus mushroom, the cancer-inducing doses of these chemicals or mushroom used in the animal experiments, the total amounts of these chemicals or mushroom needed to induce cancer in these mice, and the estimated total amounts of these chemicals or mushroom needed to induce cancer in humans. By adding the estimated amounts of chemicals needed to induce cancer and by comparing it with the amount of raw mushroom needed to induce the same effect, it becomes obvious that we have accounted for less than 2% of the carcinogenic components of theAgaricus bisporus mushroom. Since some unavailable data handicapped this assessment, it should be regarded as tentative and subject to further adjustment.
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  • 37
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    Springer
    International journal of biometeorology 34 (1990), S. 42-48 
    ISSN: 1432-1254
    Keywords: Briths ; Humans ; Solar wind ; Geomagnetism ; Melatonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.
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  • 38
    ISSN: 1432-1009
    Keywords: Reservoir ; Fisheries ; Breeding and wintering waterbirds ; Raising water levels ; Habitat change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A new, higher dam was installed at Kerkini Reservoir in 1982, causing habitat and landscape disruption. A decrease in the area of grassland and shallow water areas, the rapid disappearance of reedbeds, the appearance of beds ofNymphaea, and the disappearance of half the forest area were all observed between 1982 and 1991. With the new hydrological regime, a lacustrine system was created, with an extensive, rather deep (4–8 m), pelagic zone favorable for the development of coarse fish species throughout the year. After 1982, an increase in fishing effort and a change in the relative abundance of fish species in the catch, including the disappearance of eels and wels, were observed. The impact of the rise in the water level of breeding aquatic birds led to a general decline in species typical of marshy habitats in favor of species preferring deeper open water habitats. A decrease was recorded in bird species that feed largely on invertebrates and to a lesser extent fish (e.g., glossy ibis) and that require extensive shallow feeding areas. There was a decline in geese, whose nests were regularly flooded, and a major increase in piscivorous birds, particularly diving birds (e.g., cormorants), which prefer deeper open water and benefitted directly from the large increase in coarse fish biomass. The disappearance of birds breeding in flooded meadows (e.g., black-winged stilts) and of those restricted to reedbeds (e.g., marsh harrier) occurred from 1983. Over the same period, the changes in populations of wintering birds at Kerkini were different from those occurring in other wetlands in northern Greece. The changes recorded in the populations of wintering birds at Kerkini did not therefore result from overall regional trends but from the major habitat modifications that occurred to this wetland. As for breeding birds, strictly piscivorous species increased greatly as a result of the increased availability of fish, but also due to the appearance of many suitable night roosting sites (flooded trees) and to the great increase in the area of open water greater than 2 m deep. Today, Kerkini has become the most important breeding site in Greece for a majority of colonial waterbirds. In contrast, wintering shorebirds practically disappeared. The many changes recorded in the status of breeding and wintering birds at Kerkini can mostly be explained by the changes that occurred in the functioning of the ecosystem and in the habitat structure following the inauguration of the new hydrological regime. These changes did not all occur at the same time: some were immediate and others required a delay before they could be detected.
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  • 39
    ISSN: 1432-1009
    Keywords: Fisheries ; Phosphorus ; Contaminants ; Ecosystem ; Management ; Simulation model ; Great Lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter (Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies of dominant organisms) that should be corrected in order to make reliable management decisions.
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  • 40
    Electronic Resource
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    Environmental management 7 (1983), S. 151-160 
    ISSN: 1432-1009
    Keywords: Grass carp ; Biological control ; Nuisance aquatic weeds ; Fisheries ; Aquaculture ; Reproductive requirements ; Arkansas management plan ; Sterile hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grass carp (Ctenopharyngodon idella Val.) were introduced into the United States in 1963 as potential biological control agents for nuisance aquatic weeds. Since that time an oftentimes bitter controversy has raged over its effects on sportfishing, and its possible natural reproduction and naturalization in North America. This review considers the history, ecology, and present status of grass carp in the United States in light of the voluminous scientific research conducted since its importation. Particular attention is given to the role of grass carp in the fisheries management plans of Arkansas. Recent development of a sterile, triploid grass carp hybrid may lead to widespread use of grass carp to control nuisance aquatic weeds in culturally eutrophicated waters of the United States.
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  • 41
    ISSN: 1432-1009
    Keywords: Flushing ; Scouring ; Channel Maintenance ; Fisheries ; Trinity River
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The operation of Trinity and Lewiston Dams on the Trinity River in northern California in the United States, combined with severe watershed erosion, has jeopardized the existence of prime salmonid fisheries. Extreme streamflow depletion and stream sedimentation below Lewiston have resulted in heavy accumulation of coarse sediment on riffle gravel and filling of streambed pools, causing the destruction of spawning, nursery, and overwintering habitat for prized chinook salmon (Salmo gairdnerii) and steelhead trout (Oncorhynchus tschawytscha). Proposals to restore and maintain the degraded habitat include controlled one-time remedial peak flows or annual maintenance peak flows designed to flush the spawning gravel and scour the banks, deltas, and pools. The criteria for effective channel restoration or maintenance by streambed flushing and scouring are examined here, as well as the mechanics involved. The liabilities of releasing mammoth scouring-flushing flows approximating the magnitude that preceded reservoir construction make this option unviable. The resulting damage to fish habitat established under the postproject streamflow regime, as well as damage to human settlements in the floodplain, would be unacceptable, as would the opportunity costs to hydroelectric and irrigation water users. The technical feasibility of annual maintenance flushing flows depends upon associated mechanical and structural measures, particularly instream maintenance dredging of deep pools and construction of a sediment control dam on a tributary where watershed erosion is extreme. The cost effectiveness of a sediment dam with a limited useful economic life, combined with perpetual maintenance dredging, is questionable.
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    Environmental management 20 (1996), S. 523-539 
    ISSN: 1432-1009
    Keywords: Water control ; Floodplain ; Fisheries ; Bangladesh ; Chandpur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bangladesh is a very flat delta built up by the Ganges—Brahmaputra—Meghna/Barak river systems. Because of its geographical location, floods cause huge destruction of lives and properties almost every year. Water control programs have been undertaken to enhance development through mitigating the threat of disasters. This structural approach to flood hazard has severely affected floodplain fisheries that supply the major share of protein to rural Bangladesh, as exemplified by the Chandpur Irrigation Project. Although the regulated environment of the Chandpur project has become favorable for closed-water cultured fish farming, the natural open-water fishery loss has been substantial. Results from research show that fish yields were better under preproject conditions. Under project conditions per capita fish consumption has dropped significantly, and the price of fish has risen beyond the means of the poor people, so that fish protein in the diet of poor people is gradually declining. Bangladesh is planning to expand water control facilities to the remaining flood-prone areas in the next 15–20 years. This will cause further loss of floodplain fisheries. If prices for closed-water fish remain beyond the buying power of the poor, alternative sources of cheap protein will be required.
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    Environmental management 3 (1979), S. 133-144 
    ISSN: 1432-1009
    Keywords: Coastal zone Management ; Fisheries ; Marshes ; Wetlands ; Louisiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper examines causes and consequences of wetland losses in coastal Louisiana. Land loss is a cumulative impact, the result of many impacts both natural and artificial. Natural losses are caused by subsidence, decay of abandoned river deltas, waves, and storms. Artificial losses result from flood-control practices, impoundments, and dredging and subsequent erosion of artificial channels. Wetland loss also results from spoil disposal upon wetlands and land reclamation projects. Total land loss in Louisiana's coastal zone is at least 4,300 ha/year. Some wetlands are converted to spoil banks and other eco-systems so that wetland losses are probably two to three times higher. Annual wetland losses in the Barataria Bay basin are 2.6% of the wetland area. Human activities are the principal determinants of land loss. The present total wetland area directly lost because of canals may be close to 10% if spoil area is included. The interrelationship between hydrology, land, vegetation, substrate, subsidence, and sediment supply are complicated; however, hydrologic units with high canal density are generally associated with higher rates of land loss and the rate may be accelerating. Some cumulative impacts of land loss are increased saltwater intrusion, loss of capacity to buffer the impact of storms, and large additions of nutrients. One measure of the impact is that roughly $8–17 × 106 (U.S.A.) of fisheries products and services are lost annually in Louisiana. Viewed at the level of the hydrologic unit, land loss transcends differences in local vegetation, substrate, geology, and hydrology. Land management should therefore focus at that level of organization. Proper guideline recommendations require an appreciation of the long-term interrelations of the wetland estuarine system.
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  • 44
    ISSN: 1432-0878
    Keywords: Skeletal muscles ; Ultrastructure ; Exercise ; Glycogen ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these “depleted” type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.
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  • 45
    ISSN: 1573-5133
    Keywords: Chondrichthyes ; Elasmobranchs ; Fisheries ; Ageing methods ; Growth rates ; Gestation periods ; Maturity ; Vertebral bands ; Weight-length relationships ; Life histories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent 〉80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at 〉225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L∞ = 291 cm TL, K = 0.153, t0 = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L∞ = 329 cm TL, K = 0.073, to = −2.2 yr.
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    Environmental biology of fishes 2 (1977), S. 241-259 
    ISSN: 1573-5133
    Keywords: Production ; Fisheries ; Population dynamics ; Energetics ; Fishes ; Competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Production rates of seven species of fishes were determined for one year in a 0.95 ha pond. Total annual production of all fishes in the pond was 209 g m−2y−1 (after the subtraction of 16.2 g m−2y−1 of negative production). Over 90% of the production occurred in the months of June through September, with young-of-the-year fishes contributing 84% of the total. When Y of Y fishes shifted to benthic diets in the spring, the small biomass of benthos available could not sustain the large biomas of fish. Severe competition for the available food then resulted in decreased production rates for the entire fish taxocene.
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    Environmental biology of fishes 7 (1982), S. 177-180 
    ISSN: 1573-5133
    Keywords: Temperature ; Behavior ; Ecology ; Fisheries ; Fish ; Marine juveniles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Sixteen yearling winter flounder, tested individually for 3-day periods in electronic shuttleboxes, voluntarily occupied an 8–27°C range of temperature, with a modal final thermal preferendum of 18.5°C (mean 18.7°C, median 19°C, midpoint 17.5°C, s.d. 1.9°C, S k + 0.33). The locomotor activity pattern of the yearling fish in the laboratory was markedly nocturnal, with mean hourly nocturnal activity exceeding mean hourly diurnal activity by a factor of 3.4. Maximum activity occurred at 0300 EST, minimum activity at 1400 EST. While activity generally increased with temperature, a local activity minimum occurred at 18.7°C, coinciding with the 24-hour mean final thermal preferendum. Comparison of these laboratory data with previously published field data suggest that behavioral responses to temperature and light play significant roles in determining age- and size-specific differences in seasonal depth stratification and onshore-offshore distributions in this species.
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    Environmental biology of fishes 30 (1991), S. 253-271 
    ISSN: 1573-5133
    Keywords: Rockfish ; Longevity ; Reproductive value ; Fisheries ; Scorpaenidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan) show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries (ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing means that indices of population changes, more representative of fishing effects than the catch rate index presently used, are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes. Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time frame of the species' life history, and that of management strategies, is stressed.
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    Environmental biology of fishes 35 (1992), S. 187-203 
    ISSN: 1573-5133
    Keywords: California ; Elasmobranchs ; Exploitation ; Fisheries ; Life history ; Tagging ; Triakidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L∞, K. and to parameters of 1536 mm. 0.082, and -2.31, respectively, for both sexes combined. The L8 value for females (1602 mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and to values were almost identical. Seasonal changes in size modes of young-of-the-year leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation.
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    Environmental biology of fishes 45 (1996), S. 219-235 
    ISSN: 1573-5133
    Keywords: Ecology ; Behaviour ; Evolution ; Cichlids ; Fisheries ; Conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Ecological conditions in tropical lacustrine systems are considered by focusing on the evolution, maintenance, exploitation and vulnerability of fish communities in the African Great Lakes. The exceptionally high biodiversities in the littoral/sublittoral zones of the very ancient, deep, clear, permanently stratified rift lakes Tanganyika and Malawi, are contrasted with the simpler systems in their pelagic zones, also with biodiversity in the much younger, shallower Victoria, the world's largest tropical lake.
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    Animal cognition 1 (1998), S. 25-35 
    ISSN: 1435-9456
    Keywords: Key words Shape from shading ; Visual search ; Texture segregation ; Chimpanzees ; Humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The perception of shape from shading was tested in two chimpanzees (Pan troglodytes) and five humans (Homo sapiens), using visual search tasks. Subjects were required to select and touch an odd item (target) from among uniform distractors. Humans found the target faster when shading was vertical than when it was horizontal, consistent with results of previous research. Both chimpanzees showed the opposite pattern: they found the target faster when shading was horizontal. The same difference in response was found in texture segregation tasks. This difference between the species could not be explained by head rotation or head shift parallel to the surface of the monitor. Furthermore, when the shaded shape was changed from a circle to a square, or the shading type was changed from gradual to stepwise, the difference in performance between vertical and horizontal shading disappeared in chimpanzees, but persisted in humans. These results suggest that chimpanzees process shading information in a different way from humans.
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    Environmental biology of fishes 23 (1988), S. 141-154 
    ISSN: 1573-5133
    Keywords: Cyanide ; Diversity ; Development ; Ecology ; Environment ; Fisheries ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The biological diversity and productivity of Philippine coral reefs are threatened by siltation, destructive fishing methods, coral and shell collecting and overfishing. Destructive fishing includes: the widespread, illegal use of explosives; poisons such as sodium cyanide; muro-ami and kayakas fishing; and trawling. The recent decline in catch rates threatens the livelihood of 700 000 near-shore subsistence fishermen who catch 55% of the total landings. The new government under Corazon Aquino wishes to protect the marine environment through the creation of a viable marine conservation management plan, enforcement of existing laws and through cooperation between government, non-government and international agencies to provide education and research. The Department of Agriculture, which has the authority for fisheries, has designated the International Marinelife Alliance as the lead non-government agency involved with fund raising, net-training and finding alternatives to destructive fishing methods.
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  • 53
    ISSN: 1573-5133
    Keywords: Cyprinids ; Ethiopia ; Morphotypes ; Food-niche ; Biodiversity ; Feeding ; Evolution ; Fisheries ; Resource partitioning ; Piscivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis In October–December 1990, the large barbs (Barbus) that contribute more than 35% of the catch in lake Tana (northern Ethiopia) were studied. Previous authors (Rüppell 1837, Boulenger 1902,1911, Bini 1940) described from 6 to 23 (sub)species for the lake. Banister (1973) lumped all of these into one subspecies: Barbus intermedius intermedius Rüppell,1837. We found that the Lake Tana Barbus could be readily categorized in at least 13 discrete morphotypes, some of which were already distinguished by local fishermen. None of the known descriptions are adequate to distinguish the barbs unambiguously, which is important for monitoring and management of developing fisheries. Intermediates between morphotypes were rare (〈 10%). By applying canonical discriminant analysis on a set of 17 morphometric characters (including some directly associated with feeding) our initial morphotype-distinction was confirmed. Also, differences between the morphotypes in distribution, related to depth and substratum were found, as well as differences in intestinal contents, a key to the food-niche. The high number of piscivorous morphotypes (8 out of 13) was striking as piscivory is relatively rare among cyprinids. Piscivory was found to be highly correlated with morphological (feeding related) characters. The presence of discrete morphotypes, that also differ in food-niche and distribution, strongly suggests that several distinct populations exist, that may be (partly or completely) reproductively segregated. Knowledge about these populations, that may represent separate units of fish stock, is of crucial importance for the management of sustainable fisheries and protection of the biodiversity in Lake Tana. It is possible that several species or even a unique cyprinid species flock are present, that urgently need protection.
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    Environmental biology of fishes 27 (1990), S. 303-308 
    ISSN: 1573-5133
    Keywords: Fish introductions ; Africa ; Cichlids ; Barbus ; Haplochromis ; Lake management ; Fisheries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Cyprinid fishes apparently constituted the major part of the original fish fauna in Lake Luhondo, Rwanda, at least until 1934. At that time only three species, all cyprinids, were known from the lake:Barbus neumayeri, a small barbel, very common in the lake (described from the lake asBarbus luhondo) and two larger cyprinid species:Barbus microbarbis andVaricorhinus ruandae. These two large species were probably not very common in the lake. Between 1935 and 1938 some youngTilapia were introduced into Lake Luhondo. Since then and certainly since 1952 the large cyprinids seem to have disappeared completely from the lake. The smallBarbus neumayeri has become extremely rare; at present it survives only in some small tributaries of the lake. In the lake itselfTilapia andHaplochromis species are now the dominant fauna. A survey of the available information is given.
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    Environmental biology of fishes 43 (1995), S. 381-391 
    ISSN: 1573-5133
    Keywords: Fisheries ; Irrigation ; Reproductive seasonality ; Sarotherodon galilaeus ; Species richness ; Water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis A preliminary study of the ecology and commercial fish catches was carried out in the Toho-Todougba, Ahouangan and Dati lakes (1500 ha) in southern Benin (West Africa) over a period of 18 consecutive months. Water quality, species richness, and the reproductive biology of the dominant species, Sarotherodon galilaeus, were examined. Unlike Lagoon Toho-Todougba, lakes Ahouangan and Dati are less favourable for fish production because of their high total iron content and their relative low pH. The study revealed the existence of 19 species belonging to eleven (11) families: 16 species in Lagoon Toho-Todougba,12 in Lake Ahouangan, and 7 in Lake Dati. Lakes Ahouangan and Dati had a relatively high faunal similarity whereas Lagoon Toho-Todougba exhibited a relatively low faunal similarity with the former systems. In Lagoon Toho-Todougba, six cichlid species were the most important component of the fishery: Sarotherodon galilaeus, Tilapia guineensis, T. zillii, T. mariae, Chromidotilapia guntheri, Hemichromis fasciatus. Three catfish species Chrysichthys auratus, Clarias agboyiensis, and Clarias lazera were harvested in low abundances. Some other fish, such as Polypterus senegalus senegalus, Protopterus annectens and Heterotis niloticus were captured sporadically, with H. niloticus appearing more consistently in catches than the others. Although not abundant, Gymnarchus niloticus and the African pike, Hepsetus odoe, were almost always present in the catches. Ctenopoma kingsleyae appeared only in Ahouangan. Some predatory species, such as Notopterus afer and Xenomystus nigri, are encountered only in lakes Ahouangan and Dati. In Lagoon Toho-Todougba, Sarotherodon galilaeus had a sex ratio (♂: ♀) of 0.49:1, and size at maturation was estimated as 12.3 cm TL. The spawning period extended from May to September with the peak occurring in July. Fecundity was correlated to log-body length (r = 0.74) and log-body weight (r = 0.76). Fish catches were estimated at 389 kg ha−1 year−1; about 73% of which was Sarotherodon galilaeus. The overexploitation of juvenile fish and the use of this lagoon for the irrigation of palm tree plantations have reduced fish recruitment and mean size.
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    Environment, development and sustainability 2 (2000), S. 277-304 
    ISSN: 1573-2975
    Keywords: Systems of Knowledge ; Local Knowledge ; Fisheries ; Resource Management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Sociology
    Notes: Abstract During the last 20 years, the existence of rich systems of local knowledge, and their vital support to resource use and management regimes, has been demonstrated in a wide range of biological, physical and geographical domains, such as agriculture, animal husbandry, forestry and agroforestry, medicine, and marine science and fisheries. Local knowledge includes empirical and practical components that are fundamental to sustainable resource management. Among coastal-marine fishers, for example, regular catches and, often, long-term resource sustainment are ensured through the application of knowledge that encompasses empirical information on fish behaviour, marine physical environments, fish habitats and the interactions among ecosystem components, as well as complex fish taxonomies. Local knowledge is therefore an important cultural resource that guides and sustains the operation of customary management systems. The sets of rules that compose a fisheries management system derive directly from local concepts and knowledge of the resources on which the fishery is based. Beyond the practical and the empirical, it is essential to recognise the fundamental socio-cultural importance of local knowledge to any society. It is through knowledge transmission and socialisation that worldviews are constructed, social institutions perpetuated, customary practices established, and social roles defined. In this manner, local knowledge and its transmission, shape society and culture, and culture and society shape knowledge. Local knowledge is of great potential practical value. It can provide an important information base for local resources management, especially in the tropics, where conventionally-used data are usually scarce to non-existent, as well as providing a shortcut to pinpoint essential scientific research needs. To be useful for resources management, however, it must be systematically collected and scientifically verified, before being blended with complementary information derived from Western-based sciences. But local knowledge should not be looked on with only a short-term utilitarian eye. Arguments widely accepted for conserving biodiversity, for example, are also applicable to the intellectual cultural diversity encompassed in local knowledge systems: they should be conserved because their utility may only be revealed at some later date or owing to their intrinsic value as part of the world's global heritage. At least in cultures with a Western liberal tradition, more than lip-service is now being paid to alternative systems of knowledge. The denigration of alternative knowledge systems as backward, inefficient, inferior, and founded on myth and ignorance has recently begun to change. Many such practices are a logical, sophisticated and often still-evolving adaptation to risk, based on generations of empirical experience and arranged according to principles, philosophies and institutions that are radically different from those prevailing in Western scientific circles, and hence all-but incomprehensible to them. But steadfastly held prejudices remain powerful. In this presentation I describe the 'design principles' of local knowledge systems, with particular reference to coastal-marine fishing communities, and their social and practical usefulness. I then examine the economic, ideological and institutional factors that combine to perpetuate the marginalisation and neglect of local knowledge, and discuss some of the requirements for applying local knowledge in modern management.
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    International Journal of Quantum Chemistry 1 (1967) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 1-6 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    International Journal of Quantum Chemistry 1 (1967), S. 7-12 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 13-36 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 37-102 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    International Journal of Quantum Chemistry 1 (1967), S. 119-119 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    International Journal of Quantum Chemistry 1 (1967) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    International Journal of Quantum Chemistry 1 (1967), S. 139-145 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On analyse quelques calculs d'atomes à plusieurs électrons. On établit que pour les atomes neutres l'énergie d'interaction électron-électron peut être représentée approximativement par un multiple constant de l'énergie d'interaction électron-noyau. Par conséquent l'énergie totale de ces atomes-ci dépend d'une façon très simple du nombre atomique.
    Abstract: Berechnungen für Atome mit vielen Elektronen sind analysiert. Es ist gezeigt dass für neutrale Atome die Wechselwirkungsenergie zwischen Elektronen von einem konstanten Vielfache der Wechselwirkungsenergie zwischen den Elektronen und dem Kern wohl approximiert werden kann. Eine Folge dieses Satzes ist dass die Totalenergie dieser Atome in sehr einfacher Weise von der Atomnummer abhängt.
    Notes: Many-electron atom calculations are analyzed. It is proved that for neutral atoms to a good approximation the electron-electron interaction energy is a constant multiple of the electron-nucleus interaction energy. A consequence of the above theorem is that the total energy of these atoms shows a very simple dependence on the atomic number.
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    International Journal of Quantum Chemistry 1 (1967), S. 161-167 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On étudie les informations relatives aux indices de réfraction pour quelques gaz pour obtenir des formules analytiques. De celles-ci on obtient le coéfficient du terme principal de l'interaction de longue portée entre deux corps ainsi que celui de l'interaction de longue portée non-additive entre trois corps. On calcule les coéfficients correspondants pour des mélanges des gases He, Ne, A, Kr, Ze, H2, N2 et CH4, l'erreur probable étant 5%.
    Abstract: Gewisse Brechungsindexinformationen für mehrere Gase sind zu analytischen Formeln angepasst. Von diesen berechnet man die Koeffiziente des Prinzipalglieds der Wechselwirkung zwei entfernter Körper und der non-additiven Wechselwirkung drei entfernter Körper. Koeffizienten sind für Mischungen der Gase He, Ne, A, Kr, Xe, H2, N2 und CH4 berechnet, mit einem wahrscheinlichen Fehler von 5%.
    Notes: The refractive index data for various gases are fitted to analytical formulae from which may be calculated the coefficient of the leading term of the long-range two-body interactions and the coefficient of the leading term of the long-range non-additive three-body interactions. Coefficients are obtained for mixtures of the gases He, Ne, A, Kr, Xe, H2, N2 and CH4, the probable error being 5%.
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  • 68
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    International Journal of Quantum Chemistry 1 (1967), S. 147-159 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a construit un programme pour un ordinateur électonique pour calculer les bandes d'énergie suivant l'approximation “tight-binding”. Ce programme a été employé pour des cristaux de α zirconium sans et avec de l'oxygène dissout. Les bandes d'énergie résultantes et les distributions des orbitales correspondantes représentent une quantité énorme d'information numérique. Un autre programme a été construit pour analyser les populations des bandes occupées. Ce programme-ci va réduire considérablement l'information produite. Seulement les bandes occupées sont décrites dans un nombre de directions dans l'espace k. Les nombres d'occupation sont sommés pour les orbitales de nombres quantiques egaux, l et |m|, et sont calculés pour chaque bande en fonction de k.
    Abstract: Ein Maschinenprogramm ist für “tight-binding” Berechnungen von Energiebänder geschrieben worden. Dieses Programm ist auf Kristallen von α Zirkonium mit und ohne gelästen Sauerstoff angewendet. Die resultierenden Energiebänder und Orbitalverteilungen repräsentieren eine sehr grosse Menge von numerischer Information. Ein anderes Programm ist nun geschrieben worden für Populationsanalyse der besetzten Bänder. Dieses Programm reduziert die Informationsmenge in ansehnlicher Weise, und nur besetzte Bänder sind für einige verschiedene Richtungen im k Raum gegeben. Die Besetzungszahlen sind für Orbitale mit gleichen Quantenzahlen l und |m| summiert, und für jedes Band als eine Funktion von k erhalten.
    Notes: An electronic-computer programme has been written by the author for calculations of energy bands in the tight-binding approximation. This programme has been applied to crystals of α zirconium with and without dissolved oxygen. The resulting energy bands and orbital distributions represent an enormous amount of numerical data. Another programme has now also been written by the author for population analysis of the occupied bands. This programme will reduce the resulting output considerably, and only occupied bands are represented in a number of directions in k space. The occupation numbers are summed up for orbitals with equal quantum numbers l and |m|, and are found for each band as a function of k.
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  • 69
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    International Journal of Quantum Chemistry 1 (1967) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 187-190 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On emploie la méthode de Tomonaga pour déterminer la fréquence des oscillations collectives résultant de l'excitation d'un électron dans le systeme d'électrons π d'un hydrocarbure aromatique regardé comme un gaz d'électrons libres en deux dimensions. Les fréquences calculées et mesurées s'accordent parfaitement, bien que la coordonnée collective ne fût pas conjugée au moment collectif.
    Abstract: Man berechnet, mit der Methode von Tomonaga, die Frequenz kollektiver Schwingungen, verursacht von der Aufregung eines Elektrons in dem System von π Elektronen eines aromatischen Kohlenwasserstoffes, das als ein Gas freier Elektronen angesehen wird. Berechnete und Experimentelle Frequenzen stimmen sehr wohl überein, obgleich die kollektive Koordinate nicht zu dem kollektiven Impuls konjugiert sei.
    Notes: Considering the π electrons in aromatic hydrocarbons as forming a two-dimensional free-electron gas, the Tomonaga method has been followed to determine the frequency of collective oscillations when an electron is excited in these systems. The calculated and experimental frequency have been found to be in excellent agreement, although the collective coordinate was not conjugate to the collective momentum in these systems containing only few free π electrons.
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  • 71
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
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  • 72
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    International Journal of Quantum Chemistry 1 (1967), S. 225-241 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a calculé l'énergie d'interaction de longue portée entre deux atomes d'hydrogène jusqu'au second ordre de la perturbation. Tous les états du système provenant de l'un des atomes dans un état 1s et l'autre dans l'un des états 2s ou 2p ont été considérés. L'énergie, représentée par une série en puissances inverses de la distance internucléaire, R, a été calculée jusqu'aux termes d'ordre R-8. On estime que les énergies d'interaction sont correctes pour R 〉 15 u.a. On a calculé aussi d'une façon précise l'énergie d'interaction entre deux atomes d'hydrogène dans leurs états fondamentaux jusqu'aux termes d'ordre R-10. Les résultats pour l'état B′ 1∑u+ sont employés pour discuter l'énergie de dissociation expérimentale de H2, D2, et HD. Pour H2 on démontre que toutes les valeurs de l'énergie de dissociation, obtenues de limites d'absorption expérimentales (les courbes d'énergie potentielle étant employées pour éliminer l'effet de rotation) sont consistantes. Cependant l'énergie totale résultante de H2 est plus grande que la valeur théorique la plus exacte.
    Abstract: Die Wechselwirkungsenergie zwei entfernter Wasserstoffatome ist mit Störungstheorie zweiter Ordnung berechnet. Alle Zustände des Systems, die von einem der Atome in einem 1s Zustand und von dem anderen in einem 2s oder 2p Zustand entstehen können, sind berücksichtigt. Die Energie, die als eine Reihe in reziproken Potenzen des Kernabstands R ausgedrückt ist, ist bis Glieder in R-8 berechnet. Die resultierenden Wechselwirkungsenergien sind wahrscheinlich für R 〉 15 a.E. zuverlässig. Genaue Wechselwirkungsenergien für zwei Wasserstoffatome im Grundzustand sind auch bis Glieder in R-10 berechnet. Die Resultate für den B′ 1∑u+ Zustand sind benutzt um die experimentellen Dissoziationsenergien von H2, D2, und HD im Grundzustand zu untersuchen. Für H2 sind alle Werte der Dissoziationsenergie, die von experimentellen absorptionsgrenzen mit Anwendung von den berechneten Potentialenergiekurven um den Effekt der Rotation zu absondern, erhalten sind, in befriedingender Weise übereinstimmend. Die resultierende Totalenergie von H2 ist aber grösser als der richtigste theoretische Wert.
    Notes: Long-range interaction energy between two hydrogen atoms has been computed in the second order of the perturbation theory. All states of the system arising when one of the atoms is in the 1s and the other in the 2s or 2p state have been considered. The energy represented by a series expansion in inverse powers of the internuclear distance, R, has been computed up to the terms in R-8. The results are believed to give reliable interaction energies for R 〉 15 a.u. Accurate interaction energy for two ground-state hydrogen atoms has also been obtained up to the terms in R-10. Results for the B′ 1∑u+ state are employed to discuss the experimental ground-state dissociation energy of H2, D2, and HD. For H2 all values of the dissociation energy obtained from various experimental absorption limits, by using the computed potential energy curve to separate off the effect of rotation, are shown to be satisfactorily consistent. The resulting total energy of H2 is, however, higher than the most accurate theoretical value.
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    International Journal of Quantum Chemistry 1 (1967), S. 191-215 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On présente un modèle pour estimer les ionicités de molécules et d'ions complexes. Ce modèle est basé sur une minimisation de l'énergie totale par la méthode des énergies d'ionisation différentielles. L'effet sur les énergies des corrections de Madelung est considéré. Il est possible d'améliorer la méthode en calculant les énergies de la liaison covalente.On a fait des calculs de type Wolfsberg-Helmholz dans le cadre de ce modèle, en incorporant les corrections de Madelung. Ces corrections-ci rendent les courbes d'énergie d'ionisation du métal moins raides et les énergies d'ionisation des ligandes sont presque invariables par rapport aux charges. Ceci crée une situation qui a été jusqu'ici imposée artificiellement en choisissant les énergies d'ionisation des ligandes de façon à créer des termes désirables dans le déterminant séculaire de Wolfsberg-Helmholz. On démontre que l'effet de l'énergie de Madelung constitue l'influence primaire pour décrire l'ionicité et l'énergie totale d'un chromophore; on démontre que les effets de la liaison covalente sont secondaires quand les ligandes et l'atome central ont des électronégativités assez différentes.
    Abstract: Ein Modell für die Abschätzung von Ionizitäten in Moleküle und Komplexionen wird beschrieben. In diesem Modell wird die Totalenergie mit der Methode der differentiellen Ionisationsenergien minimisiert. Der Effekt der Madelungkorrektionen wird berück-sichtigt, und das Modell wird durch Berechung der kovalenten Bindungsenergien verbessert.Wolfsberg-Helmholzberechungen werden für dasselbe Modell mit Madelungkorrektionen einverlei ausgeführt. Die Madelungkorrektionen machen die Ionisations-energiekurven der Metalle weniger steil; die Ionisationsenergien der ligander sind fast imvariant mit der Ladung. Dies schafft eine Situation, die bisher in künstlicher Weise durch die Wahl der Ionisationsenergien der Liganden in der Wolfsberg-Helmholzsche Methode gegeben war. Es würd gezeigt, dass die Madelungenergie das wichtigste Glied für die Beschriebung der Ionizität und der Totalenergie eines Kromophors ist, und dass diese Effekteüber die kovalente Bindung dominieren, wenn die Liganden und das Zentralatom sehr verschiedene Elektronegativitäten haben.
    Notes: A model is presented for the estimation of ionicities in molecules and complex ions. The model uses the minimization of total energy by the method of differential ionization energies. The effect of Madelung corrections to the energies is considered, and the model is refined by evaluating the covalent-bond energies.Wolfsberg-Helmholz calculations have been applied to the same type of model, also incorporating Madelung corrections. The Madelung corrections make the metal ionization energy curves less steep, and the ligand ionization energies are nearly invariant with charge. This creates a situation which has previously been artificially imposed by selecting the ligand ionization energies to give desirable terms in the Wolfsberg-Helmholz secular determinant. The effect of Madelung energy is shown to be the primary influence in describing the ionicity and total energy of a chromophore; covalent bonding effects are shown to be secondary when the ligands and the central atom have fairly different electronegativities.
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    International Journal of Quantum Chemistry 1 (1967), S. 243-249 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 285-291 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Le spectre de valeurs propres d'un système dynamique conservatif est contenu implicitement dans sa fonction de Green. Il devient explicite dans la transformée de Fourier de la fonction de Green ou de sa trace. Cette trace n'existe que dans le cas où le spectre est complètement discret. On présente des applications aux problèmes d'une particule libre, de l'oscillateur harmonique linéaire et de l'atome d'hydrogène. Dans les deux derniers cas on peut simplifier la détermination de la fonction de Green considérablement en transformant l'Hamiltonien.
    Abstract: Das Eigenwertspektrum eines konservativen, dynamischen Systems ist in impliziter Weise in seiner Greenschen Funktion enthalten. Es wird in dem Fouriertransform der Greenschen Funktion oder deren Spur explizit. Der Spur existiert nur wenn das Spektrum durchaus diskret ist. Diese Methoden sind auf die Probleme des freien Teilchens, des linearen harmonischen Oszillators und des Wasserstoffatoms angewendet. In den zwei letzteren Fällen kann die Bestimmung der Greenschen Funktion wesentlich mit Transformationen des Hamiltonoperators vereinfacht werden.
    Notes: The energy eigenvalue spectrum for a conservative dynamical system is contained implicitly in its Green's function. It becomes explicit in the Fourier transform of either the Green's function or its trace. The trace exists only when the spectrum is entirely discrete. Applications are made to the free particle, the linear harmonic oscillator, and the hydrogen atom. In the latter two cases determination of the Green's function can be considerably simplified by similarity transformations on the Hamiltonian operator.
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  • 77
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a calculé l'état fondamental et trois états ionisés de N2 pour plusieurs distances intérnucléaires selon l'approximation SCF—MO—LCAO. Les coéfficients linéaires ainsi que les constantes d'écran des orbitales atomiques ont été optimisés. On a calculé des courbes de l'énergie potentielle les constantes moléculaires ωe, ωexe, Be, αe, et Re pour les états cités. Les résultats calculés sont comparés aux données expérimentales ainsi qu'aux résultats d'autre calculs ab initio.
    Abstract: Die SCF—MO—LCAO Methode wird auf den Grundzustand und auf drei jonisierten Zustände von N2 für mehrere Kernabstände angewendet. In diesen Berechnungen werden sowohl die lineare Koeffizienten als auch die Abschirmungskonstanten der Atomorbitale optimiert. Die Molekülkonstanten ωe, ωexe, Be, αe, und Re sind für die zitierten Zustände aus den Potenzialenergiekurven berechnet worden. Die berechneten Resultate werden mit experimentellen Angaben und mit Resultaten anderer ab initio Berechnungen verglichen.
    Notes: The self-consistent-field molecular-orbital method in LCAO (linear combination of atomic orbitals) approximation is applied to the ground and three ionized states of N2 at a number of internuclear distances for the computation of the potential energy curves. In these calculations both the linear coefficients and the screening constants of the atomic orbitals have been optimized. The molecular constants ωe, ωexe, Be, αe, and Re have also been calculated for the above states from the computed potential energy curves. The computed spectral results are compared with the experimental data as well as with the results reported by others from ab initio calculations.
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    International Journal of Quantum Chemistry 1 (1967) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 1 (1967), S. 271-283 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Une fonction d'onde, qui n'est pas une fonction propre exacte, peut, si elle satisfait à des conditions analytiques propres, ětre regardée comme représentant la configuration initiale d'un état non-stationnaire. Pendant son évolution suivante dans le temps le système quantique expose implicitement son spectre total de valeurs propers. On établit une méthode pour le calcul direct du spectre des valeurs propres de l'énergie, basée en principe sur l'analyse de Fourier du système quantique évoluant. La fonction spectrale est développement est tronqué, ce qui est nécessaire dans toute application, la fonction spectrale correspondante représente un spectre moyen de valeurs propres. Une approximation alternative mène à la méthode des moments. En augmentant le nombre des termes on peut améliorer le spectre calculé. Dans certains cas on peut éluder la méthode des moments, s'il est possible d'obtenir en forme clos l'action de l'opérateur d'évolution. Ceci revient a trouver une solution de l'équation de Schrödinger dépendant du temps. Les différentes méthodes de spectroscopie de valeurs propres sont appliquées au probleme de l'oscillateur harmonique.
    Abstract: Eine Wellenfunktion die nicht eine exakte Eigenfunktion ist, kann, unter gewissen analytischen Bedingungen als repräsentierend eine Initial-konfiguration eines nichtstationären Zustands betrachtet werden. Während ihre folgende Entwicklung in der Zeit, legt der Quantensystem in impliziter Weise seinen ganzen Eigenwertspektrum dar. Eine Methode, die im Prinzip auf Fourieranalysis des entwickelnden Systems basiert ist, ist für die direkte Berechung des Eigenwertspektrums benutzt. Die Spektralfunktion ist als eine Momentenentwicklung ausgedrückt, die eine Funktion der Mittelwerte der Potenzen des Hamiltonoperators ist. Wenn die Entwicklung abgebrochen ist, was notwendig ist in alle praktische Anwendungen, ist die entsprechende Spektralfunktion als ein Eigenwertspektrum im Mittel repräsentiert. Eine alternative Approximation führt zu die Quanten-mechanische Methode der Momente. Als die Nummer der Glieder wächst, wird das berechnete Spektrum scharfer und genauer. In gewissen Fällen kann man die Momentenentwicklung entgehen, wenn die Wirkung des Evolutions-operators in geschlossener Form ausdrückt werden kann. Dies ist eine Lösung der Zeitabhängigen Schrödingergleichung zu finden gleichwertig. Die Methoden der Eigenwertspektroskopie werden auf den harmonischen Oszillator angewendet.
    Notes: A wave function which is other than an exact eigenfunction, if it obeys appropriate analytical conditions, can be considered to represent the initial configuration of a nonstationary state. In the course of its subsequent time development the quantum system exhibits implicitly its entire eigenvalue spectrum. A method based, in principle, on Fourier analysis of the evolving quantum system is applied to the direct calculation of the energy eigenvalue spectrum. The spectral function is expressed as a moment expansion, in terms of expectation values of powers of the Hamiltonian. When the expansion is truncated, as it must be in any practical application, the corresponding spectral function represents a smeared-out eigenvalue spectrum. An alternative approximation leads to the quantum-mechanical method of moments. As the number of terms is increased, the computed spectrum becomes sharper and more accurate. In certain cases the moment expansion can be circumvented, if the action of the evolution operator can be evaluated in closed form. This is equivalent to finding some solution of the time-dependent Schrödinger equation. The various methods of eigenvalue spectroscopy are applied to the harmonic oscillator.
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  • 80
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    International Journal of Quantum Chemistry 1 (1967), S. 321-325 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On établit une nouvelle méthode variationelle pour calculer la probabilité de transitions défendues, ainsi que des bornes supérieures etinférieures del'élément matriciel correspondant.
    Abstract: Ein neues Variationsprinzip für die Wahrscheinlichkeit verbotener Übergänge wird angegeben. Man erhält auch obere und untere Grenzen für das entsprechende Matrixelement.
    Notes: A new variational principle for the probability of forbidden transitions is derived. Upper and lower bounds for the corresponding matrix element are given.
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    International Journal of Quantum Chemistry 1 (1967), S. 311-319 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On établit une méthode générale pour calculer des structures atomiques, basée sur le principe “des fonctions radiales différentes pour des électrons différents”. On décrit les connections entre cette méthode-ci et les méthodes ordinaires. Dans la méthode proposée les complications additionelles entrent seulement dans le traitment des variables radiles. Les règles générales pour les calculs nouveaux sont formulées.
    Abstract: Eine verallgemeinerte Methode für Atomstrukturberechnungen wird charakterisiert. Man braucht in dieser Methode verschiedene Radialfunktionen für verschiedene Elektronen. Der Zusammenhang zwischen den verallgemeinerten und den gewöhnlichen Methoden wird beschreibt. Spezille Komplikationen treten nur in der Behandlung der radiller Variabeln auf. Die allgemeine Regeln für Berechnungen mit der neuen Methode werden formuliert.
    Notes: The extended method of calculation of atomic structures is characterized. This method is understood as the use of as many radial orbitals as there are electrons in the atom under consideration. The process of passing from the ordinary method of calculation to the extended one is described. In the method proposed the additional complications appear within the confines of dealing with radial variables only. The general rules for carrying out the calculations, in applying the extended method, are formulated.
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    International Journal of Quantum Chemistry 1 (1967), S. 293-310 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Après une courte discussion de la signification physique du choix de base dans les calculs moléculaires, on discute la nature et la définition d'une base d'orbitales atomiques pour des calculs restreints, l'idée principale étant de remplacer par exemple les orbitales ordinaires de Slater 2s et 2p par des orbitales atomiques hybridées et promues. S'il faut définir les orbitales atomiques dans le cadre d'une certaine interprétation de l'activité des molécules, l'hybridization et la promotion peuvent devenir nécessaires.On considère explicitement deux sortes de conditions qui peuvent être soutaitables pour une base restreinte: (1) Les hybrides recherchées doivent ětre dirigées le long des liaisons et satisfaire en même temps au critère de recouvrement maximum; (2) Les orbitals atomiques doivent satisfaire à la condition que le moment dipolaire électrique d'une molécule polyatomique, qui est décrite dans un cadre sémi-empirique, peut être représenté comme le moment dipolaire du système de charges de liaison localisé aux noyaux.La dernière condition est traitée en détail et l'on montre qu'elle implique une neutralisation des moments atomiques et des moments de recouvrement. On donne les équations définissant les orbitales atomiques en question.Dans le cours du traitement mathématique on démontre certains résultats portant sur l'expression du moment dipolaire d'une molécule et sur la définition des charges atomiques nettes. De ces expressions-ci il découle que pour des systèmes avec des intégrales de recouvrement petites, les populations atomiques peuvent être représentées par des sommes de carrés des coéfficients des orbitales atomiques orthogonalisées.Des applications seront présentées dans la seconde partie de cet article.
    Abstract: Nach einer kurzen Diskussion der physikalischen Bedeutung der Wahl von Bais in molekularen Berechungen, wird die Natur und Definition einer Atomorbitalbasis für begrenzte Berechnungen diskutiert, um die Möglichkeit zu untersuchen, ob gewöhnliche 2s und 2p Slater-orbitale gegen hybridisierte-beförderte Atomorbitale ersetzbar sind. Wenn die Orbitale in der Rahme einer gegebenen Interpretation für das Betragen der Moleküle definiert werden musst, können Hybridisation und Förderung notwendig werden.Bedingungen zweier Art für begrenzte Atomorbitalsysteme werden in expliziter Weise betrachtet: (1) Die Hybriden sollen längs der Bindung gerichtet sein, und zugleich das Kriterium maximaler Überlappung befriedigen; (2) Es soll möglich sein, den elektrischen Dipolmoment eines polyatomischen Molekül als den Diplmoment des Systems von an den Kernen lokalisierten Bindungsladungen repräsentieren.Die letzte Bedingung ist ausführlich behandelt und eis ist gezeigt, dass sie eine Aufhebung der Atom- und Überlappungsmomente bedeutet. Die Gleichungen, die die Atomorbitale definieren, welche diese Bedingung befriedigen, werden gegeben.Einige allgemeine Resultate betreffend die Ausdrücke für den Dipolmoment eines Moleküls, und die Definition “reine” Atomladungen werden gegeben. Diese zeigen, dass, für Systeme mit kleinen Überlappungs-integralen, können die Atompopulationen als Summen von Quadraten der Koeffiziente der orthogonalisierten Atomorbitale repräsentiert werden.Anwendungen dieser Resultate werden in Teil II dargestellt worden.
    Notes: After a brief discussion of the physical significance of the choice of the basis in molecular calculations, the nature and definition of an atomic-orbital basis for use in limited calculations is discussed, in view of the possibility of replacing, say, ordinary 2s and 2p Slater orbitals by appropriate hybridized-promoted atomic orbitals. It is indicated that, if the orbitals must be defined in connection with a given interpretation scheme for the behavior of molecules, hybridization and promotion may be necessary.The two kinds of conditions one may wish to impose on a restricted atomic-orbital set are explicitly considered. The first is that the atomic orbitals should be hybrids directed along the bonds and at the same time satisfy the maximum overlap criterion; the other is the requirement that the atomic orbitals should be such that the electric dipole moment of a polyatomic molecule described in terms of a semiempirical bond-orbital scheme should be expressed as the dipole moment of the system of bond charges located at the nuclei.The latter condition is treated in detail, showing that it implies a cancellation of atomic and overlap moments. The equations defining the atomic orbitals satisfying the condition in question are given.In the course of the mathematical treatment some general results concerning the expression of the dipole moment of a molecule and the definition of net atomic charges are given, showing that, for systems where overlap integrals are low, the atomic populations can be taken as sums of the squares of the coefficients of orthogonalized atomic orbitals.Applications of the results will be presented in part II.
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  • 83
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    International Journal of Quantum Chemistry 1 (1967), S. 327-335 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The ground-state electronic energy of Be is calculated using the method of biorbitals (SCF-BI). In this method the wave function is represented by an antisymmetrized product of identical pair functions. The basic set used to develop the biorbitals consists of the Watson s and p orbitals. The pair function is presumed to describe a singlet pair state. The energy associated with this function is minimized using a steepest descent procedure. A value of 0.0414 a.u. was found for the correlation energy, which is 44% of the total correlation energy. The SCF-BI method is compared with the CI method. The relationships are established between the expansion coefficients of both methods. The occupation numbers of orbitals are calculated.
    Abstract: Die elektronische Energie des Grundzustands des Be-Atoms wird mit der Methode von Biorbitalen berechnet. Die Wellenfunktion wird in dieser Methode von einem antisymmetrischen Produkt identischer Paarfunktionen repräsentiert. Die Biorbitale werden in Watson's s und p Orbitale entwickelt. Die angewendeten Paarfunktionen beschreiben Singlettzustände. Die Energie ist mit einer Methode von steilstem Abstieg minimisiert worden. Man findet 0, 0414 a.E. für die Korrelationsenergie, d.h. 44% der theoretischen Korrelationsenergie. Die SCF-BI-Methode wird mit der Konfigurationswechselwirkungsmethode verglichen. Die Beziehungen zwischen den Koeffizienten der beiden Methoden werden abgeleitet und die Besetzungszahlen gegeben.
    Notes: L'énergie électronique de l'état fondamental de l'atome Be a été calculée en utilisant la méthode des biorbitales (SCF-BI) dans laquelle la fonction d'onde est représentée par un produit antisymétrisé de fonctions de paire identiques. Les fonctions de base sur lesquelles les biorbitales sont développées sont les orbitales s et p données par Watson. Les fonctions de paire introduites correspondent à des états singulets. L'énergie a été minimisée directement par un procédé de descente selon la pente maximale. On trouve 0,0414 u.a. pour l'énergie de corrélation soit 44% de l'énergie de corrélation théorique. On compare la méthode (SCF-BI) à la méthode (IC) d'interaction de configuration. On établit des relations entre les coefficients dans les deux méthodes. On donne les nombres d'occupation des orbitales.
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  • 84
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    International Journal of Quantum Chemistry 1 (1967), S. 349-355 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The C5H5- ion has been investigated ab initio in the equilibrium distance of the centers, taking all 36 electrons into account, using the Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. A total energy of -189.42 a.u. and an ionization energy (electron affinity of C5H5) of 0.9 eV were found. A most significant result is that one π orbital is more strongly binding than four σ orbitals.
    Abstract: On présente un calcul ab initio de la molécule C5H5- pour la distance à l'équilibre des noyaux, basé sur Allgemeines Programmsystem/SCF-MO-LC (LCGO) Methode. Tous les 36 électrons ont été considérés. On trouve pour l'énergie totale -189.42 u.a. et pour l'énergie d'ionisation (l'affinité électronique de C5H5) 0.9 eV. L'une des orbitales π est plus liante que quatre des orbitales σ.
    Notes: Das C5H5- wird im Gleichgewichtsabstand der Zentren unter Berücksichtigung aller 36 Elektronen ab initio mit Hilfe des Allgemeinen Programmsystems/SCF—MO—LC(LCGO) Methode berechnet. Es ergibt sich eine Gesamtenergie von -189,42 a.E. Die Ionisierungsenergie (Elektronenaffinität des C5H5) beträgt 0,9 eV. Bei den Einteilchenenergien sind in energetischer Folge den π-Zuständen σ-Zustände eingelagert.
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  • 85
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    International Journal of Quantum Chemistry 1 (1967), S. 357-359 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The C6H6 has been investigated ab initio for the equilibrium distance of the centers, taking into account all 42 electrons, using the Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. A total energy of -227.27 a.u. and an ionization energy of 8.5 eV were found. Further one of the π orbitals was more strongly binding than some of the σ orbitals.
    Abstract: On présente un calcul ab initio de la molécule C6H6 pour la distance à l'équilibre des noyaux, basé sur Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. Tous les 42 électrons on été considérés. On trouve pour l'énergie totale -227.27 u.a. et pour l'énergie d'ionisation 8.5 eV. L'une des orbitales σ est plus liante que quelques-unes des orbitales π.
    Notes: Das C6H6 wurde im Gleichgewichtsabstand der Zentren unter Berücksichtigung aller 42 Elektronen ab initio mit dem Allgemeinen Programmsystem/SCF—MO—LC(LCGO) Methode berechnet. Es ergab sich eine Gesamtenergie von -227.27 a.E. und eine Ionisierungsenergie von 8.5 eV. Ferner wurde gefunden, dass den Einelektronen π-Zuständen in energetischer Reihenfolge σ-Zustände eingelagert sind.
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  • 86
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    International Journal of Quantum Chemistry 1 (1967), S. 337-347 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: En mécanique non-relativiste le potentiel monocentrique Coulombien admet des constantes du mouvement qui forment les composantes du vecteur de Runge-Lenz. On déduit une constante du mouvement additionelle pour le problème analogue bicentrique. Le résultat, qui est correct dans une espace d'un nombre arbitraire de dimensions, peut être employé en mécanique classique ainsi qu'en mécanique quantique. Cependant il n'est plus valable si l'on considère les corrections relativistes. On discute l'effet d'autres centres Coulombiens et l'effet d'une variation de la forme du potentiel. En particulier on déduit une constante du mouvement pour un potentiel bicentrique avec des termes harmoniques ainsi que des termes coulombiens. On note une relation entre ces constantes du mouvement et la séparation de l'Hamiltonien en coordonnées sphéroïdes. Enfin on discute l'application de ces résultats-ci au problème do molécule-ion de l'hydrogène dans l'approximation adiabatique. La nouvelle constante du mouvement est responsable de la non-validité observée de la règle de non-croisement des courbes d'énergie potentielle.
    Abstract: Das monozentrische Coulombpotential hat in nichtrelativistischer Mechanik zusätzliche Bewegungskonstanten, die Komponenten des Runge-Lenz Vektors bilden. Von einem Studium dieses Vektors wird eine neue Bewegungskonstante für das entsprechende bizentrische Problem abgeleitet. Das Resultat ist in einem Raum willkürlicher Dimension gültig, und kann in sowohl klassischer Mechanik als Quantenmechanik angewendet werden. Es ist aber nicht mehr gültig, wenn relativistische Korrektionen betrachtet werden, die die zusätzliche Symmetrie des monozentrischen Coulombpotentials zerstören. Die Abhängigkeit anderer Coulombzentra und der Form des Potentials wird untersucht. Eine Bewegungskonstante wird für ein bizentrisches Potential mit sowohl Coulomb und harmonischen Termen abgeleitet. Die Beziehung zwischen diesen Bewegungskonstanten und der Separation des Hamiltonoperators in sphäroiden Koordinaten wird beachter. Mit dieser neuen Bewegungskonstante kann man die Nichtgültigkeit des Überschneidungsverbotes der Potentialkurven des Wasserstoffmolekülions erklären.
    Notes: The one-centre Coulombic potential gives rise, in non-relativistic mechanics, to additional constants of the motion which form the components of the Runge-Lenz vector. By a study of this vector, an extra constant of the motion is derived for the corresponding two-centre problem. The result holds quite generally in a space of arbitrary dimension and is applicable to both classical and quantum mechanics; but breaks down when relativistic corrections, which destroy the extra symmetry of the one-centre Coulombic potential, are taken into account. The effect of further Coulombic centres and of varying the form of the potential is briefly discussed. In particular a constant of the motion is derived for a two-centre potential which has both Coulombic and simple harmonic terms. The relationship between these constants of the motion and the separation of the Hamiltonian into spheroidal coordinates is noted (this had previously been known only for the two-centre Coulomb problem in three-dimensional space). Finally the application to the hydrogen molecule ion, treated in the adiabatic approximation, is pointed out. The extra constant of the motion is seen to account for an observed apparent breakdown in the noncrossing rule for the potential energy curves.
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  • 87
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    International Journal of Quantum Chemistry 1 (1967), S. 361-364 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The C3H6 has been investigated ab initio, taking all 24 electrons into account, using the Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. Variation of the C—C distance gives a total energy of -116.02 a.u. at a C—C distance of 2.91 a.u. The ionization energy was found to be 10.33 eV.
    Abstract: On présente un calcul ab initio de la molécule C3H6 basé sur Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. Tous les 24 électrons on été considérés. Variant la distance C—C on obtient l'énergie totale -116.02 u.a. pour la distance C—C 2.91 u.a. L'énergie d'ionisation correspondante est 10.33 eV.
    Notes: Das C3H6 wurde unter Berücksichtigung aller 24 Elektronen ab initio mit dem Allgemeinen Programmsystem/SCF—MO—LC(LCGO) Methode berechnet. Es ergab sich nach Variation des C—C Abstandes ein Minimum der Gesamtenergie von -116.02 a.E. bei einem C—C Abstand von 2.91 a.E. Die Ionisierungsenergie wurde zu 10.33 eV bestimmt.
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  • 88
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    International Journal of Quantum Chemistry 1 (1967), S. 365-368 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The C2H4 was investigated ab initio for the equilibrium distance of the centers, taking all 16 electrons into account, using the Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. A total energy of -76.77 a.u. and an ionization energy of 10.55 eV were found.
    Abstract: On présente un calcul ab initio de la molécule C2H4 pour la distance à l'équilibre des noyaux, basé sur Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. Tous les 16 électrons ont été considérés. On trouve, pour l'énergie totale -76.77 u.a. et pour l'énergie d'ionisation 10.55 eV.
    Notes: Das C2H4 wird im Gleichgewichtsabstand der Zentren unter Berücksichtigung aller 16 Elektronen ab initio unter Verwendung des Allgemeinen Programmsystem/SCF—MO—LC(LCGO) Methode berechnet. Es ergibt sich eine Gesamtenergie von -76.77 a.E. Die Ionisierungs-energie beträgt dabei 10.55 eV.
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  • 89
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    International Journal of Quantum Chemistry 1 (1967), S. 369-372 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Using the results of ab initio calculations, by comparison of the “1s orbital energies” of the C atom in the compounds C6H6, C5H5-, C3H6 (cyclopropane), C2H4 as well as at the C atom itself the bond electrons were found to have a significant influence on the inner electrons. The reason for this is pointed out and an explanation is given. The connection between the bonding and this “1s orbital energy” change as well as the importance of this result for quantum-chemical “models” is discussed.
    Abstract: On compare les énergies des orbitales 1s de l'atome C libre et de l'atome C dans C6H6, C5H5-, C3H6 (cyclopropane), C2H4. On trouve une influence significative des électrons de valence sur les électrons de la couche intérieure. On discute la raison de cette influence et ses conséquences pour les modèles de la chimie quantique.
    Notes: Durch Vergleichen der “1s-Einteilchenenergien” an den C Atomen in den Verbindungen C6H6, C5H5-, C3H6 (Cyclopropan), C2H4 sowie am freien C Atom wird im Rahmen von ab initio - Rechnungen gezeigt, dass die inneren Elektronen von den Bindungsvorgängen wesentlich beeinflusst sind. Die Ursachen werden diskutiert und eine Erklärung dafür angegeben. Der Zusammenhang dieser Energieänderungen mit den Bindungsverhältnissen, sowie die Bedeutung dieser Tatsache für gewisse Modellvorstellungen werden besprochen.
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  • 90
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    International Journal of Quantum Chemistry 1 (1967), S. 373-378 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The CH4 molecule has been investigated ab initio, for four different distances RC—H and one distortion of a triangle HCH about the equilibrium condition, taking all 10 electrons into account, using the Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode. The equilibrium distance RC—H was estimated to 2.053 a.u., the minimum of the total energy to -40.06 a.u., the heat of formation to 17.0 eV and the ionization energy to 14.8 eV. For the breathing force constant and the force constant of the twisting vibration a ω1 of 3139 cm-1 and a ω2 of 1865 cm-1 were found.
    Abstract: On présente un calcul ab initio de la molécule CH4, basé sur Allgemeines Programmsystem/SCF—MO—LC(LCGO) Methode, pour tous les 10 électrons, quatre distances différentes C—H et pour une distorsion d'un triangle HCH. On trouve pour la distance à l'équilibre C—H 2.053 u.a., l'énergie totale -40.06 u.a., l'énergie de formation 17.0 eV, l'énergie d'ionisation 14.8 eV, la constante de force des vibrations de pulsation 3139 cm-1 et la constante de force des vibration de torsion 1865 cm-1.
    Notes: Das CH4 wurde unter Berücksichtigung aller 10 Elektronen mit dem Allgemeinen Programmsystem/SCF—MO—LC(LCGO) Methode für 4 verschiedene Abstände RC—H und für die Verdrillung eines Dreieckes HCH gegenüber der Gleichgewichtslage (s. Abbildung 1) berechnet. Es ergab sich im Minimum eine Gesamtenergie von -40.06 a.E., eine Bildungsenergie von 17.0 eV und eine Ionisierungsenergie von 14.8 eV. Der Bindungsabstand wurde zu RC—H = 2.053 a.E. bestimmt. Die sich ergebenden Kraftkonstanten lieferten die Frequenzen ω1 = 3139 cm-1 und ω2 = 1865 cm-1.
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  • 91
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    International Journal of Quantum Chemistry 1 (1967), S. 379-401 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: By means of the HMO method a postulate by Clar is justified. According to this postulate certain localized benzene-like regions exist in condensed aromatic hydrocarbons. A measure of the benzene character, butene character, etc., of certain parts of these molecules is derived and a simple method to calculate it is described. The importance of these measurements for discussions of chemical reactivity is pointed out.
    Abstract: Mit Hilfe der HMO Methode wird gezeigt, dass das Postulat von E. Clar, gewisse Sechsring-Einheiten in kondensierten Aromaten stellen lokale benzoide Gebiete dar, berechtigt ist. Eine Masszahl (Character order) für den benzoiden, butenoiden usw. Charakter bestimmter Teile kondensierter Aromaten wird abgeleitet und ein einfaches Rechenverfahren zu ihrer Ermittlung angegeben. An Hand der Charakterogramme von 41 kondensierten Aromaten wird die Bedeutung dieser Zahlen für die Diskussion der chemischen Reaktivität aufgezeigt.
    Notes: Partant de la méthode HMO on vérifie qu'un postulate de Clar est justifié. D'après ce postulat il existe dans les hydrocarbures aromatiques condensés certaines régions localisées de caractère benzènoide. On propose un indice pour le caractère benzèneoide, butènoide, etc., de certaines parties de ces molécules, et on présente une méthode simple pour calculer ces indices. On discute l'importance de ces indices pour la réactivité chimique.
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  • 92
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    International Journal of Quantum Chemistry 1 (1967), S. 421-425 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a calculé, pour un déterminant de Slater projeté sur un sous-espace de spin défini, les fonctions de densité pour deux électrons, définies par McWeeny.
    Abstract: Die Zweielektronenfunktionen von McWeeny, sind für eine Spin-projizierte Slaterdeterminante berechnet worden.
    Notes: The two-particle density functions introduced by McWeeny are calculated for a spin-projected Slater determinant.
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  • 93
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    International Journal of Quantum Chemistry 1 (1967), S. 403-419 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: La fonction d'onde d'un système à n électrons dans la méthode Hartree-Fock généralisée (EHF) est définie (Löwdin, Phys. Rev. 97, 1509 (1955)) comme le meilleur déterminant de Slater construit de spin-orbitales d'une flexibilité complète et projeté sur un sous-espace de symmétrie correcte. On compare cette fonction à l'interaction de configurations équivalente pour l'état 1S d'un atome à deux électrons. On démontre qu'il existe dans ce cas-ci un nombre infini de solutions du problème variationnel avec des énergies inférieures à celles de la fonction Hartree-Fock ordinaire, et avec des spin-orbitales satisfaisant à toutes les conditions de l'extrémum. On présente deux méthodes pour obtenir les spin-orbitales EHF. Une application à l'état fondamental de l'hélium avec une base contenant 4(s), 3(p0, 2(d0)) et 1(f0) orbitales de Slater donne 90% de l'énergie de corrélation.
    Abstract: Die verallgemeinerte Hartree-Fock Funktion eines Systems mit n Elektronen ist als die beste projizierte Slaterdeterminante, die aus vollständig allgemeinen Einelektronfunktionen gebaut ist (Löwdin, Phys. Rev. 97, 1509 (1955)). Die Konfigurationswechselwirkungsfunktion, die zu einer verallgemeinerten Hartree-Fock Funktion äquivalent ist, wird für den 1S Zustand eines Zweielektronenatoms diskutiert. Es wird gezeigt, dass in diesem Falle unendlich viele Lösungen des Variationsproblems existieren, die tiefere Energien als die gewöhnliche Hartree-Fock Funktion haben. Zwei Lösungsmethoden werden beschriebn. Mit einer Basis von 4(s), 3(p0), 2(d0) und 1(f0) Slaterorbitalen wird 90% der Korrelationsenergie des Heliumatoms im Grundzustand erhalten.
    Notes: The extended Hartree-Fock (EHF) wave function of an n-electron system is defined (Löwdin, Phys. Rev. 97, 1509 (1955)) as the best Slater determinant built on one-electron spin orbitals having a complete flexibility and projected onto an appropriate symmetry subspace. The configuration interaction equivalent to such a wavefunction for the 1S state of a two-electron atom is discussed. It is shown that there is in this case an infinite number of solutions to the variational problem with energies lower than that of the usual Hartree-Fock function, and with spin orbitals satisfying all the extremum conditions. Two procedures for obtaining EHF spin orbitals are presented. An application to the ground state of Helium within a basic set made up of 4(s), 3(p0), 2(d0) and 1 (f0) Slater orbitals has produced 90% of the correlation energy.
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  • 94
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    International Journal of Quantum Chemistry 1 (1967), S. 451-461 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The formalism of the LCAO—SCF—CO method is described. This method enables the theoretical study of conjugated periodic systems. In these systems some integrals of the SCF operator matrix elements are evaluated by a semi-empirical procedure.
    Abstract: Die LCAO—SCF—CO Methode für periodische, konjugierte Systeme wird beschrieben. Eine semi-empirische Methode für Berechnung der Integrale, die die Matrixelemente des SCF-Operators bilden, wird angegeben.
    Notes: On décrit le formalisme de la méthode LCAO—SCF—CO permettant d'étudier les propriétés des systèmes périodiques conjugés et un procédé semi-empirique pour évaluer les intégrales intervenant dans les éléments de matrice de l'operateur du champ autocohérent de ces systèmes.
    Additional Material: 1 Tab.
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  • 95
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 2 (1968), S. 563-563 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 2 (1968), S. 651-662 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On propse comme une modification de la méthode SCF-MO-LCGO, une méthode qualitative et on traite le naphthaléne comme illustration. Les rèsultats de ce calcul sont en bon accord avec l'experience. On discute les avantages de la mèthode proposée pour les calculs de la chimie quantique.
    Abstract: Eine Modifikation des SCF-MO-LCGO-Verfahrens in Form einer qualitativen ab initio Methode wird angegeben und als testrechnung auf Naphthalin angewendet. Die Ergebnisse stehen im Einklang mit der Erfahrung. In diesem Zusammenhang wird das Verfahre in den allgemeinen Rahmen gestellt und seine Möglichkeiten diskutiert.
    Notes: A modification of the SCF-MO-LCGO method is proposed in the form of a qualitative ab initio method. Naphthalene is treated as a test case; good agreement between calculated and experiemental results is obtained. The capabilities of the method for quantum-chemical calculations are discussed.
    Additional Material: 1 Ill.
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  • 97
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 1 (1967) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 98
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 7 Tab.
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  • 99
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 131-139 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical approximation for the hypersurface E (pr-approximation) is given using the two- and three-center-functions pλμ and rμνλ, which is valid for any number N of atoms and is invariant with respect to the number of centers in its analytical structure (rule of construction). This is valid too if N is reduced either by the association of atoms or by transitions to infinity. pλμ can be fixed by two-center-systems. But rμνλ is still free except for the fulfilling of some simple requirements. The rule of construction proposed for E is an example for using so-called analytical computers.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 149-167 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The general formulas which are convenient for cluster analysis of a configuration interaction wave function are presented. These formulas are then used for cluster analysis of the “complete” configuration interaction wave functions of the π-electronic models of benzene and butadiene obtained with a semiempirical method of the Pariser-Parr-Pople type using three different parameterizations. For butadiene the calculations are carried out with Hückel, Hartree-Fock, and Brueckner molecular orbitals. The results clearly indicate that Sinanoǧlu's statement [1, 2], concerning the relative unimportance of the linked parts of the tetraexcited state coefficients in the ci expansion, is justified for these delocalized systems.
    Additional Material: 5 Tab.
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