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SCF perturbation theory and intermolecular interactions
Author(s) -
Basilevsky M. V.,
Berenfeld M. M.
Publication year - 1972
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.560060317
Subject(s) - coulomb , perturbation (astronomy) , intermolecular force , perturbation theory (quantum mechanics) , interaction energy , physics , statistical physics , exchange interaction , classical mechanics , quantum mechanics , molecule , ferromagnetism , electron
A self‐consistent perturbation theory is derived in the framework of Roothaan's MOLCAO procedure for closed shell systems. Contrary to previous investigations which have considered only one particle perturbations, two particle perturbation operators are considered. Expressions for the first‐order density matrix and first‐ and second‐order energy corrections are obtained. A diagram formulation of the complete perturbation expansion is presented. The results are applied to the treatment of the intermolecular interaction problem. The interaction energy is represented as a sum of several contributions: Coulomb, exchange, resonance, polarization and exchange repulsion. A semi‐empirical version of the theory is suggested which explicitly involves all the physically significant energy terms and may be useful for the investigation of complex systems.