Heitler-London Theory of Stereoselection

Abstract

One important goal of this work is the development of qualitative VB theories which can be profitably applied to diverse chemical problems. For reasons that will become clear in this and future works, we define the following brands of Approximate HL (AHL) theory:

• a) AHL theory in which we set G and R_n equal to zero and we truncate each T_n and U_n so that they include terms which are zero, first, or, second order in AO overlap. This brand of HL theory will be denoted by AHL*.

• b) AHL theory in which we set G and R_n equal to zero but we do not truncate T_n and U_n. This brand of HL theory will be denoted by AHL°.

• c) AHL theory in which we set only R_n equal to zero and we truncate T_n and U_n as indicated in (a). This brand of HL theory will be denoted by AHL≠.

• d) AHL theory in which we set R_n equal to zero but no further approximations are made. This will be simply referred to as AHL° theory.