TOPOLOGICAL ASPECTS OF CHEMICAL-REACTIVITY - ELECTRON CORRELATION IN THE COURSE OF CHEMICAL-REACTIONS

The second order similarity index g(RP), which has been proposed recen tly as a new means for a qualitative characterization of correlation e ffects in chemical reactivity, was generalized by incorporation into a topological model of the overlap determinant method. The resulting ap proach, which provides information about the variation of electron cor relation during chemical reactions, was applied to the investigation o f several selected pericyclic reactions. Consistent with what can be e xpected, the role of electron correlation was found to be the most cri tical for transition states or other transient species near the top of the energy barrier. The systematic differences in the extent of elect ron correlation between allowed and forbidden reactions are also discu ssed.