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  • Theoretical, Physical and Computational Chemistry  (5)
  • Wiley-Blackwell  (5)
  • Elsevier
  • Frontiers Media
  • Institute of Physics
  • 1
    Electronic Resource
    Electronic Resource
    Scaling behavior of energy functionals of highly complex electron distributions (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 125-131 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In highly extended (mesoscopic) molecular networks or solid-state systems, one-electron states with an extremely complex (multifractal) internal structure commonly appear at intermediate length scales. It is shown that multifractality is not compatible with the concept of electron density. Physical intuition suggests that electron densities should be smooth both at atomic distances and close to the macroscopic limit. Special care must be taken, however, in studying density-based energy functionals at intermediate length scales due to the nonexistence of the density itself. In this contribution, the extension and practical calculation of some energy functionals for multifractal structures are discussed and statistical (scaling) properties are studied as well.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 125-131, 1998
    Additional Material: 8 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Correlation-corrected energy band (level) structures of low-dimensional systemsIn memory of a good friend and a great scientist, Prof. Jean-Louis Calais. (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 631-635 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: First, several reminiscences are recalled about the author's encounters with such a beautiful person as Professor Jean-Louis Calais. Since Jean-Louis was very much interested - among other things - in the correlation problem of solids, different methods are reviewed for the correlation correction of the energy bands of 1D and 2D periodic systems as well for the levels of 1D nonperiodic chains. The results obtained show a very good agreement with experiment for the fundamental gap and exciton spectra of different polymers, for the mechanical properties of polyethylene, as well for other not-here-described physical properties of different polymeric systems. The coding of these methods for the relativistic case is in progress. © 1997 John Wiley & Sons, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    Outlines of a general framework of cancer initiation in the cell (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 64 (1997), S. 379-385 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: According to the central dogma of molecular biology, information flows in the living cell from DNA through RNA to proteins. Therefore most investigations of cancer initiation try to explain these effects by carcinogen binding to, or radiation hits on, DNA which lead to the first steps of the malignant transformations. On the other hand, recent detailed theoretical investigations have shown that proteins are good disordered hopping conductors (their conductivity is in the order of good conducting amorphous glasses). Their conductivity can be substantially influenced by binding of chemicals or by the effects of radiation if they cause conformational changes (as recent calculations have shown). These effects can also destroy bonds or generate new bonds in proteins. If the affected proteins are regulatory proteins, they can be inactivated in both ways. Namely, on the basis of Warburg's experiments, one can postulate that if the hindrance of oxygen metabolism leads to fermentation, and with it to the malignant transformation, this means also the hindrance of electron flow in the Szent-Györgyi-Krebs cycle. In other words the hindrance of electron transport in this cycle most probably has the same effect as the lack of oxygen, which in this way most probably leads again to a malignant transformation. Finally the inactivation of regulatory enzymes can influence also the regulation of the expression of oncogenes. If in this way oncogenes become overactivated (or antioncogenes become inactive), the changes started by the inactivation of regulatory enzymes become hereditary. It seems that if we look at the cell as a complicated self-regulatory system, primary changes both at their DNA or regulatory protein molecules caused by external agents can disturb its self-regulation and transform it in this way into another stationary, possibly precancerous, state.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 379-385, 1997
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Statistical electron densities (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 64 (1997), S. 85-93 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is known that in numerous interesting systems one-electron states appear with a multifractal internal structure. Physical intuition suggests, however, that electron densities should be smooth both at atomic distances and close to the macroscopic limit. Multifractal behavior is expected at intermediate length scales, with observable nontrivial statistical properties in considerably, but far from macroscopically sized clusters. We have demonstrated that differences of generalized Rényi entropies serve as relevant quantities for the global characterization of the statistical nature of such electron densities. Asymptotic expansion formulas are elaborated for these values as functions of the length scale of observation. The transition from deterministic electron densities to statistical ones along various lengths of resolution is traced both theoretically and by numerical calculations.    © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 85-93, 1997
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Quantum mechanical/molecular mechanical self-consistent Madelung potential method for treatment of polar molecular crystals (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 38-50 
    Details
    ISSN: 0192-8651
    Keywords: quantum mechanics ; molecular mechanics ; self-consistent Madelung potential ; polar molecular crystals ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The self-consistent Madelung potential (SCMP) approach for calculating molecular wave functions for a subunit embedded in a symmetrical environment constituted by the copies of the subunit is implemented with semiempirical NDDO model Hamiltonians and supplemented with empirically parameterized dispersion-repulsion interaction potentials. This model yields sublimation enthalpies in good agreement with available experimental data for a series of molecular crystals, including imidazol, benzimidazole, urea, urethane, dicyaneamide, formamide, uracil, cytosine, maleic anhydride, succinic anhydride, and 1,3,5-triamino-2,4,6-trinitro-benzene. The SCMP-NDDO method, which avoids difficulties concerning the parametrization of charges in the molecular mechanics force fields, is proposed mainly for the treatment of molecular crystals with large unit cells. It might be particularly useful where important charge reorganization is expected under the effect of the crystal field. Charge distributions, obtained by the SCMP and the simple dielectric cavity self-consistent reaction field models, are compared and analyzed.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 38-50, 1998
    Additional Material: 2 Ill.
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