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  • 1
    Electronic Resource
    Electronic Resource
    Structure and properties of non-classical polymers (1993)
    Springer
    Theoretical chemistry accounts 86 (1993), S. 353-367 
    Details
    ISSN: 1432-2234
    Keywords: High-spin non-alternant polymers ; Nature of spin exchange interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The investigations on alternant non-classical (non-Kekulé) polymers [1, 2] (ANCP) have been extended to a class of quasi-one-dimensional non-alternant non-classical polymers (NANCP). The energy spectra and the effective spin exchange between the unpaired electrons in the NANCP are investigated theoretically. As for the ANCP, the energy spectrum of the NANCP is characterized by a wide energy gap in which there is a half-filled band (HFB) of degenerate non-bonding molecular orbitals (NBMO). The occurrence of a NBMO is a topological property of the considered non-alternant systems, and is explained with an approach which originates from the Sachs theorem. The effective spin exchange interaction within the HFB of a wide variety of model polymers was calculated. It is shown that the potential (Coulomb) and the indirect exchange interaction (superexchange) are the main components of the effective ferromagnetic interaction. The ground state of the 1D-NANCP is a high-spin one, as in the case of the ANCP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01128522
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  • 2
    Electronic Resource
    Electronic Resource
    The band gap of alternant 1D π-electron systems (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 51 (1994), S. 173-180 
    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: Within the framework of the AMO-EHF approximation for the Hubbard model, it is shown that the band gap ΔE of an arbitrary regular alternant 1D π-system (polymer), having a singlet ground state, is different from zero, i.e., the ground state is a dielectric one. At least one of the three components of the energy gap - the topological, Δtop; the geometrical, Δgeom; or the correlation, Δcorr (combined via the equation ΔE = {Δcorr2 + (Δtop + Δgeom))2}1/2 - is different from zero. Numerical results for several 1D alternant polymers with conjugated π-systems are given. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560510307
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    Paper (German National Licenses)
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