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Spin‐independent three‐body effective valence‐shell operators: Application to molecular oxygen
Author(s) -
Kanzler Alfred W.,
Freed Karl F.,
Sheppard Maurice G.
Publication year - 1992
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.560440418
Subject(s) - valence (chemistry) , hamiltonian (control theory) , hamiltonian matrix , chemistry , matrix (chemical analysis) , ab initio , atomic physics , computational chemistry , ab initio quantum chemistry methods , many body theory , quantum mechanics , physics , molecular physics , molecule , mathematics , symmetric matrix , mathematical optimization , eigenvalues and eigenvectors , chromatography
A mathematical construction is presented that uniquely defines a set of spin‐independent effective valence‐shell Hamiltonian ( H v ) three‐body matrix elements. These spin‐independent H v matrix elements separate direct and exchange portions of the three‐body H v matrix elements and therefore provide the most natural form for comparisons with parameterization schemes of semiempirical electronic structure methods in which the three‐body matrix elements are incorporated into semiempirical one‐ and two‐body Hamiltonian matrix elements in an averaged manner. Ab initio H v three‐body matrix elements of O 2 are computed through third order of quasidegenerate perturbation theory and are analyzed as a function of internuclear distance and atomic orbital overlap to aid in understanding how these three‐body matrix elements may be averaged into semiempirical one‐ and two‐body matrix elements. © 1992 John Wiley & Sons, Inc.