A double perturbation theory for molecular complexes

✍ Scribed by E. Beretta; F. Vetrano

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 454 KB
• Volume: 7
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560070215

✦ Synopsis

Abstract

Consideration is given to the problem of interactions between molecular systems (magnetic couplings being neglected) by highlighting the fact that the main difficulty of a perturbation theory that takes into account the exchange effects, resides in the differentiated symmetry of the unperturbed state and of the state of interaction (at an overlap other than zero). This difficulty has been overcome by choosing for the Schrödinger equation of the interacting systems a particular representation on the set of unperturbed functions and by reversing the symmetry properties onto the operators. This will lead to a new equation no longer presenting any difficulties for the symmetry interconnection. This equation is used for a double perturbational expansion both in Coulomb and in exchange terms, thus obtaining general perturbation equations. Explicit solutions are provided (up to the second total order) which are briefly discussed.