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Partitioning schemes for the 2‐matrix and the pair density
Author(s) -
Morrison Robert C.,
Smith Darwin W.,
Larson Everett G.
Publication year - 1973
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.560070502
Subject(s) - wave function , density matrix , function (biology) , atom (system on chip) , statistical physics , point (geometry) , correlation , configuration interaction , physics , ground state , electron density , matrix (chemical analysis) , correlation function (quantum field theory) , order (exchange) , electronic correlation , quantum mechanics , electron , computational physics , mathematics , chemistry , computer science , geometry , excited state , finance , chromatography , evolutionary biology , dielectric , economics , quantum , biology , embedded system
Abstract Several schemes are discussed for partitioning the second‐order reduced density matrix Γ into two parts, Γ 0 and Γ′. The Γ 0 s are based on the independent particle model and the Γ′s are corrections due to electron correlation. The difficulties of choosing a Γ 0 that will serve as a suitable reference point for studying electron correlation are discussed. In order to compare alternative partitioning schemes, an atomic wave function for the 1 S ground state of the Be atom in the configuration‐interaction approximation was selected. A fifty‐two configuration wave function was computed and contour graphs were made of the total pair density Γ(1 2) and of the “correlation pair density” Γ′(1 2) for several choices of the reference Γ 0 .