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Use of symmetry‐adapted Brillouin theorem to analyze the variational content of molecular wave functions along potential energy surfaces: Application to BH 2 and PO 2
Author(s) -
Liévin Jacques,
Vaeck Nathalie
Publication year - 1997
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/(sici)1097-461x(1997)62:5<521::aid-qua9>3.0.co;2-y
Subject(s) - brillouin zone , conical intersection , potential energy , symmetry (geometry) , wave function , ab initio , conical surface , physics , quantum mechanics , intersection (aeronautics) , energy (signal processing) , computational chemistry , chemistry , mathematical physics , mathematics , geometry , engineering , aerospace engineering
The analysis of the Brillouin conditions in a chain of groups is used to explain why self‐consistent field (SCF), multiconfigurational SCF (MCSCF), or configuration interaction (CI) methods can lead to an unbalanced description of the potential energy hypersurfaces along symmetry‐broken pathways. A Wigner‐Racah formulation of the generalized Brillouin theorem is the appropriate theoretical tool for performing such an analysis. We apply this procedure to a Renner‐Teller splitting in BH 2 and to a pseudo‐Jahn‐Teller conical intersection in PO 2 . A systematic ab initio study of both systems leads to the definition of compact CASSCF wave functions which ensure a balanced description of the ground Born‐Oppenheimer potential energy surfaces. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 62: 521–541, 1997