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  • 1
    Electronic Resource
    Electronic Resource
    Hydrogen bonding in long chains of hydrogen fluoride and long chains and large clusters of water molecules (1974)
    Springer
    Theoretical chemistry accounts 34 (1974), S. 115-127 
    Details
    ISSN: 1432-2234
    Keywords: (HF)n-chains ; (H2O)n-chains ; Hydrogen bond energies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Energy band structures of one-dimensional (HF)n- and (H2O)n-chains have been calculated (1) by extrapolation of CNDO/2-MO levels to infinite chain length and (2) by the CNDO/2 crystal orbital (CO) method. In the CO-calculations interactions up to fifth neighbours have been taken into account. Both types of calculations were performed using experimental geometries and CNDO/2 minimum geometries of the corresponding dimers (HF)2 and (H2O)2. With the same geometries CO calculations on two-dimensional sheets of hydrogen bonded chains were performed too. Due to end-effects the extrapolated MO bands are much broader than the bands obtained by the CO method. In the CO calculations further neighbour interactions play a non-negligible role and hence the nearest neighbour approximation is not sufficient for an accurate description of crystals containing hydrogen bonds. MO calculations on one-dimensional chains of both systems show that the hydrogen bond energies increase with the number of monomers indicating the presence of cooperative effects. The hydrogen bond energies calculated with the CO method are usually somewhat larger than those extrapolated from the MO results. In three-dimensional networks of (H2O)n, however, the additional stabilization of clusters with respect to dimers is drastically diminished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00551362
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  • 2
    Electronic Resource
    Electronic Resource
    A density functional elongation method for the theoretical synthesis of aperiodic polymers (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 267-280 
    Details
    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
    URL: http://dx.doi.org/10.1002/qua.560520202
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  • 3
    Electronic Resource
    Electronic Resource
    Cooperativity and electron correlation effects on hydrogen bonding in infinite systems (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 52 (1994), S. 395-412 
    Details
    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: Structural and electronic properties of hydrogen-bonded infinite chains of hydrogen cyanide and formamide molecules have been investigated by the ab initio crystal orbital method using several, partly highly polarized, atomic basis sets of increasing size at the Hartree-Fock (HF) level and by including electron correlation effects in the second order of Møller-Plesset perturbation theory. The results obtained show that hydrogen bonding in molecular crystals of the type investigated is a highly cooperative phenomenon, both from the structural and energetic points of view. Comparison with clusters of up to four monomers demonstrate how various structural parameters converge toward their limiting values in the infinite system. The results obtained for infinite HCN chains show an excellent agreement with those observed for solid HCN, whereas the infinite formamide chain proves to be a reasonable model for the corresponding liquid phase. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560520213
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  • 4
    Electronic Resource
    Electronic Resource
    Perturbation theoretical investigation of electron correlation effects in infinite metallic and semiconducting polymers (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 23 (1983), S. 1239-1256 
    Details
    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: Møller-Plesset-type perturbation theory is applied to calculate electron correlation effects in infinite, periodic, metallic, and semiconducting polymers. Different possible choices of the zeroth-order Hamiltonian (symmetry adapted Hartree-Fock, spin-, and charge-density waves), the influence of the size of the atomic basis sets, lattice and conduction band sums are investigated. In the case of semiconducting systems a very efficient version of the method using optimally localized Wannier functions has been worked out. Applications include model calculations for infinite atomic hydrogen chains, the investigation of the role of correlation effects in the bond alternation and metal-insulator phase transition in polyene, different one-and many-particle effects contributing to the single-particle gap in polyene, and the calculation of correlated quasiparticle band structures using the electronic polaron model.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560230414
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of side-chain disorder on the electronic structure of proteins (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 995-1006 
    Details
    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 influence of side-chain disorder on the electronic structure of proteins has been investigated in the case of polypeptides containing two or three different amino acid residues. It has been found that due to the different potentials of different side-chain groups, the original valence and conduction bands of the homopolypeptides are split into narrow bands. The comparison of the densities of electronic states in simple homopolypeptides and in composite polymers shows that new forbidden regions in the energy spectrum of proteins may develop. The consequences of these effects for the semiconductive properties of proteins are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170514
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    Paper (German National Licenses)
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