Premium
Studies in the paired orbital method. IV. Orthogonal transformations in the virtual space
Author(s) -
Pauncz Ruben
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.560440815
Subject(s) - atomic orbital , molecular orbital , formalism (music) , complete active space , space (punctuation) , theoretical physics , computer science , physics , quantum mechanics , computational chemistry , information retrieval , chemistry , molecule , electron , art , operating system , musical , visual arts
Abstract The paired orbital method deals with the problem how to obtain the best pairing scheme in the different orbitals for the different spins ( DODS ) method. Once one has found those virtual orbitals which are the best pairs of the occupied orbitals, one can use the same formalism for the energy expression as used earlier in the alternant molecular orbital ( AMO ) method. Starting from the canonical orbitals, one performs orthogonal transformations in the virtual space until the minimum of the total energy is obtained. An illustrative calculation on the water molecule for three internuclear distances shows that the method yields 25–60% of the energy improvement obtained by a full configuration interaction method. The percentage of improvement increases with the increase of the intemuclear distance. © 1992 John Wiley & Sons, Inc.