The generalized separated electron pair model. III. An application to three localization schemes for CO

Abstract

AbstractsThe separated electron pair (SEP) model (strongly orthogonal geminals) and methods for its systematic extension have been applied to three different localization schemes for C-0.The optimum SEP wave function is obtained for the particular localization scheme that involves three equivalent bent bonds. The major corrections to the SEP model arise from one-electron transfer terms. Two-electron transfer terms were important only for those pairs that were not well localized. I t was found that the separate definitions of the total intrapair and interpair correlation energies did not depend strongly on the choice of localization scheme. worden. Die optimale sEP-Welenfunktion ist fur das besondere Lokalisierungsverfahren erhalten, das drei aquivalente "gebogene" Bindungen enthalt. Die wichtigsten Verbesserungen zum sEP-Modell entstehen aus den Einelektronenuberfihrungsgliedern. Zweielektronenuberfuhrungsglieder sind nur fur solche Paare wichting, die nicht gut lokalisiert sind. Die Definitionen der totalen Intrapaar-und Interpaarkorrelations-energien hangen von der M'ahl des Lokalisierungs-verfahren nicht stark ab.

Geminal model chemistry II. Perturbative corrections

“…[2][3][4][5][6][7] Sometimes this model is referred to as separated electron pair ͑SEP͒ theory. [8][9][10][11][12] Most prior studies focused on the total amount of correlation energy recovered by the product of strongly orthogonal geminals. It was generally concluded that the model has its limitations, primarily attributable to either lack of intergeminal correlation, 5 strong orthogonality approximation, 13 or both.…”