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All‐pair wave function and reduced variational equation for electronic systems
Author(s) -
NáraySzabó G.
Publication year - 1975
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.560090103
Subject(s) - geminal , wave function , multiplicity (mathematics) , open shell , slater determinant , curse of dimensionality , cyclobutadiene , multiplicative function , function (biology) , quantum mechanics , physics , mathematics , mathematical physics , electron , mathematical analysis , chemistry , atomic orbital , molecule , statistics , evolutionary biology , stereochemistry , biology
A new type of wave function is proposed for atomic and molecular systems. This all‐pair function is constructed of N ( N – 1)/2 identical geminals for N electrons. For systems with the highest multiplicity this is the full space part of the wave function. For closed shell systems it has to be multiplied by a Slater determinant according to the antisymmetry condition. In the case of maximal multiplicity a reduced variational equation is derived for the geminal. This equation is independent of the dimensionality of the system and contains the particle number as a multiplicative factor only. The method is extended to the closed shell case where a restriction has to be fulfilled. The reduction of the variational equation can be done only approximately. The use of identical geminals can be treated as a first approximation. An extension of the method, called the pair interdependent configuration interaction (PICI), is proposed. The special features of the method are discussed briefly.