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The valence bond calculations for conjugated hydrocarbons having 24–28 π‐electrons
Author(s) -
Wu Jian,
Jiang Yuansheng
Publication year - 2000
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/1096-987x(20000730)21:10<856::aid-jcc4>3.0.co;2-7
Subject(s) - excited state , electron , conjugated system , singlet state , chemistry , valence bond theory , covalent bond , valence electron , valence (chemistry) , ground state , atomic physics , physics , quantum mechanics , atomic orbital , organic chemistry , polymer
A novel algorithm is introduced for coding all Slater determinants in the covalent space with conserved S Z , the z component of total spin S for a classical valence bond (VB) model. It effectively minimizes the search time and the storing space in the central memory of the computer. In cooperation with symmetry reductions based on molecular point group and spin inversion, the VB calculations have been extended to benzenoid hydrocarbons of up to 28 π‐electrons that have 4×10 7 configurations. The low‐lying states of benzenoids with 24, 26, and 28 π‐electrons have been obtained for 62 species. To rationalize the aromaticity of benzenoids in a VB scheme, the resonance energy per hexagon (REPH) is defined. A linear correlation between the REPH and the energy gap of the ground (singlet) state and the first excited (triplet) state for 89 benzenoids is established. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 856–869, 2000