The orbital phase continuity principle and selection rules for concerted reactions

Abstract

In recent years the GI method(1) for electronic wavefunctions has been used to improve upon Hartree- Fock and yet retain the orbital interpretation. In the GI method we allow every orbital to be different (no double occupation restriction) and yet retain the correct spin symmetry.(2) The result is one electron per orbital and two orbitals per bond, with the orbitals generally localized near one or two nuclei (for nonaromatic systems). These orbitals are solved for self-consistentcy; however, we find that for many molecules the orbitals tend to be qualitatively similar to the familiar valence-bond functions. For example, the π orbitals of trans-1,3 butadiene are shown(2) in Figure 1. Orbitals Φ_(1a) and Φ_(1b) form one bonding pair and Φ_(2a) and Φ_(2b) form a symmetrically related bonding pair.

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