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Electron correlation described by an extended geminal model
Author(s) -
Røeggen I.
Publication year - 1981
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.560200406
Subject(s) - geminal , context (archaeology) , electronic correlation , statistical physics , physics , correlation , energy (signal processing) , quantum mechanics , mathematics , electron , chemistry , geometry , paleontology , stereochemistry , biology
A scheme for obtaining approximate solutions of the electronic Schrödinger equation is proposed in terms of an extended geminal model. The model is formulated within the context of the method of moments. The advocated approach is nonvariational, but size‐consistent as long as breaking and/or formation of new bonds can be grouped into at most four‐particle systems. The correlation energy, with respect to a separated pair approximation, is obtained as a sum of intrapair corrections and a sum of interpair corrections. An approximate model for calculating interpair correlation energies is introduced. In a test calculation on LiH, it is demonstrated that this approximate model recovers 98.0% of the correlation energy obtainable by a complete configuration interaction calculation.