ON THE ROLE OF FERMI AND COULOMB CORRELATION IN PERICYCLIC-REACTIONS

The recently proposed similarity approach to the systematic investigat ion of the changes of electron correlation during the chemical reactio ns was generalized by introducing the spin-resolved similarity indices allowing the separate investigation of correlation effects between el ectrons with parallel and antiparallel spins. The approach was applied to the investigation of several selected pericyclic reactions, both f orbidden and allowed. The main attention was devoted to the evaluation of the relative role of Fermi and Coulomb correlation, especially fro m the point of view of the differences between the allowed and forbidd en reactions.