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The generalized separated electron pair model. 1. An application to NH 3
Author(s) -
Robb M. A.,
Csizmadia I. G.
Publication year - 1970
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.560040404
Subject(s) - planar , wave function , electronic correlation , yield (engineering) , interpretation (philosophy) , chemistry , electron , simple (philosophy) , energy (signal processing) , correlation , function (biology) , correlation function (quantum field theory) , atomic physics , molecule , statistical physics , physics , molecular physics , computational chemistry , thermodynamics , quantum mechanics , mathematics , geometry , philosophy , computer graphics (images) , epistemology , evolutionary biology , biology , computer science , dielectric , programming language
The utility of the separated electron pair ( SEP ) model (strongly orthogonal geminals) is examined quantitatively, for pyramidal and planar nuclear configurations of the NH 3 molecule. The best SEP wave function computed for each species is capable of recovering about half of the correlation energy obtained by a fairly accurate configuration interaction ( CI ) calculation, (corresponding to roughly 25% of the total molecular correlation energy). It is illustrated that the model can be systematically extended with only a modest effort to yield more accurate results (about 40% of the total correlation energy). The fact that the corrections to the SEP model have a simple physical interpretation suggests that this model may be a useful starting point for “brute force” CI calculations on larger chemical systems.