ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 18 (1980), S. 515-519 
    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 potential-energy curves for the movement of proton along the hydrogen-bond direction were calculated for the parent and cations produced from the β- decay of pyridine-pyrrole labeled by tritium (3H) or carbon-14(14C). For all cations the double minimum potential is predicted to be formed, and the activation energy for the proton transfer from one well to the other is about 10.0 kcal/mol, which is much lower than that in the (NH2—H—NH2)+ ion. A positional effect of nuclear transformation is scarcely expected in 3H β- decay, whereas a slight positional effect may be expected in 14C β- decay.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 137-151 
    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 iterative transfer perturbation method is applied to polyacetylene under some kinds of local perturbations at the level of the extended Hückel method. This method rapidly provides the electronic states of nonperiodical polymers with good accuracy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 35 (1989), S. 613-628 
    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: We describe how the local equilibrium electronic structure in a large system can be determined by using the recursion method of Haydock. By applying this method to the polyacetylene molecule, the energies of each atomic site and the forces acting on each bond are estimated and the equilibrium structure near the end of polyacetylene is determined. It is found out that the degree of localization of π electrons and the bond length alternation become stronger near the end of the polyacetylene molecule.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 41-50 
    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: Geometrical and electronic structures of chlorinated polyacetylene, (CHCl)x, a precursor of one-dimensional conjugated polyyne, have been investigated through experimental and theoretical approaches. Uniaxially oriented (CHCl)x films prepared by means of prolonged FeCl3-doping of mechanically stretched polyacetylene films have been subjected to analyses. Polarized infrared absorption spectra showed a dichroism to confirm an orientation of the (CHCl)x films. On the basis of x-ray diffraction analysis, a fiber period of the (CHCl)x has been determined to be 5.2 ± 0.1 Å. Ab initio crystal orbital calculations have been performed on structural models of infinite polymer systems for the (CHCl)x. Energy gradient optimization afforded a relative stability of three different configurational structures of poly-1,2-dichloroethylene which is assumed to be a planar zigzag all-trans conformation with respect to carbon-carbon single bonds, i.e., di-syndiotactic (dst) 〉 erythro-di-isotactic (e-dit) 〉 threo-di-isotactic (t-dit) structures. In addition, the fiber period of the ist structure was calculated to be 5.2 Å, coinciding with the experimental value of the (CHCl)x. In consequence, it has been demonstrated that the prolonged FeCl3-doping of polyacetylene causes a stereospecific chlorination to yield a stereoregular dst structure of the (CHCl)x. The present results imply that a usage of this sort of chlorination through the chemical doping should provide a novel reaction design, especially to control a stereospecificity of chlorination reaction.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 267-280 
    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 elongation method, a theoretical tool to synthesize the electronic states of polymers, is applied within the framework of the density functional approach and using a linear combination of Gaussian-type orbitals. In this treatment, the wave function of a cluster is localized and the interaction with an attacking monomer is self-consistently calculated according to the Kohn-Sham equation. The reliability and the applicability of our treatment are examined by the application to a random hydrogen molecule cluster, comparing the results with those obtained by the usual diagonalization method for the whole system. The results show that this treatment efficiently provides the electronic states of the end part of aperiodic polymers. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 309-319 
    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
    Notes: An elongation method, which had already been proposed to calculate the electronic structure of aperiodic polymer efficiently, was applied to atactic polypropylene, with the approximation level of the extended Hückel method. The atomic populations thus calculated were found to be dependent sensitively on the tacticity of the polymer. Next, this elongation method was applied to the π-electron stacking system composed of ethylene and butadiene, etc. Excellent agreement was found between the elongation method and the usual extended Hückel calculations. Thus, the elongation method can confidently be applied to π-electron molecular crystal systems. Finally, the local density of states of polyacetylene with both cis-transoid and trans-cisoid structures was calculated. We found that the site with large local density of state in the valence band of a polymer chain gives large electron transfer to the site with large local density of state in the conduction band of another polymer chain. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 47 (1993), S. 449-467 
    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: A new approach to analyze the electronic structure around the local defects in a polymer chain is developed based on the cluster-series model. In this approach, by extending the cluster molecule to both sides of the defect, the size effect on electronic structure can be estimated systematically and efficiently. Moreover, through the extension process, the periodicity of electronic structure can be extracted in the form of the periodic pattern of stationary orbitals, which are molecular orbitals unaltered by the extension of the cluster. Such periodic orbitals characterize the bulk states of periodic polymer and the energy band structure can be reconstructed from them. Illustrative analyses of some kinds of local defects in all-trans-polyacetylene are presented at the ab initio STO-3G level. The effects of local defects can be detected by the deviation from periodic bulk states. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    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 elongation method based on the molecular orbital (MO) theory, which enables us to extend a polymer with any molecular fragments theoretically, has recently been developed by our group. As the next step, we introduced an approach based on the crystal orbital (CO) theory into above treatment. In the present work, the elongation method was developed at the Hartree-Fock level with CNDO/2 parameters and applied to model systems composed of the cluster series of a polymer and the molecular stacking on a surface. In the cluster-series calculations, the hydrogen molecule [(H2)n], hydrogen fluoride [(HF)n], polyethylene, and polyacetylene were created successively to approximate their one-dimensional periodic polymers by using the MO-based elongation method. In the molecular-stacking models, we described the hypothetical surface of crystal as periodically arranged hydrogen molecules by the COs, and several hydrogen molecules were stacked up on the surface one after another with the elongation procedure. Furthermore, the lattice defect on surface in which a part of stacked layer is lacking was dealt with by our approach. We also treated carbon monoxide chemisorption on a periodic magnesium chain as a more realistic model. Results for these systems support the applicability of our method for nonperiodic interactions in one- and two-dimensional large systems. © 1995 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...