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The generalized separated electron pair model. II. An application to NH 4 + , NH 3 , NH 2 − , NH 2− and N 3−
Author(s) -
Robb M. A.,
Csizmadia I. G.
Publication year - 1971
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.560050603
Subject(s) - wave function , electronic correlation , basis set , chemistry , electron , series (stratigraphy) , energy (signal processing) , atomic physics , function (biology) , limit (mathematics) , physics , computational chemistry , quantum mechanics , mathematics , mathematical analysis , density functional theory , paleontology , evolutionary biology , biology
The Separated Electron Pair (SEP) model (Strongly Orthogonal Geminals) and methods for its systematic extension has been applied to the series: NH 4 + , NH 3 , NH 2 − , NH 2− and N 3− . On going from NH 4 +to N 3− , the SEP model, in its most general form, recovers 85–75% of the intrapair correlation energy and 60–55% of the interpair correlation energy obtainable with the given basis set. The best wave functions for each species recovered about 45–50% of the total empirical correlation energy which is expected to be very close to the basis set limit. It was apparent that the SEP model yields a set of one‐electron functions that are very useful for further improvement of the wave function. This fact apparently remains true even when the SEP model itself gives very poor energies.