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Comparison of GVB and AMO approaches to the study of the PPP model of butadiene
Author(s) -
Pauncz Ruben,
Číž;ek JiřÍ
Publication year - 1990
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560370419
Subject(s) - delocalized electron , atomic orbital , valence bond theory , generalized valence bond , chemistry , valence (chemistry) , limit (mathematics) , computational chemistry , physics , quantum mechanics , mathematics , mathematical analysis , electron
The purpose of this article is the comparison of generalized valence bond ( GVB ) and the alternant molecular orbital ( AMO ) techniques both in the localized and delocalized form. The model we have chosen is the PPP model of cis ‐butadiene which is relatively simple and transparent. For equal bond lengths the AMO using delocalized orbitals is better than the GVB . For physical distances of the atoms these methods are of comparable accuracy. With the extension of the length of the central bond the GVB becomes better and is exact in the limit of two ethylenes. The AMO method using localized orbitals always gives the worst result of the three. In the limit of two ethylenes AMO in the localized and delocalized forms give the same error.