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  • 1
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 50 (1978), S. 49-65 
    ISSN: 1432-2234
    Keywords: Crystal orbital method ; Lithium chain ; Lithium hydride chain ; (BeH2) x
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ab initio calculations on the linear lithium chain, the linear lithium hydride chain and a beryllium hydride polymer have been performed using the crystal orbital method. The influence of an increase of the basis set, an increase in the number of neighbors and an increase of the density ofk-points in the Brillouin zone on the calculated equilibrium geometries and band structures has been studied systematically. A proper description of the unit cell and the interaction between neighboring cells turned out to be most important. Energy bands were found to be extremely sensitive to any variation in the basis set applied.
    Type of Medium: Electronic Resource
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