A Generalized Orbital Description of the Reactions of Small Molecules

The usual Hartree-Fock method leads to an improper description of the breaking of a bond, a problem that is overcome by the generalized valence-bond method. This method uses one orbital per electron as in the valence-bond method, but solves for the orbitals self-consistently as in the Hartree-Fock method. In this paper we consider the changes in the orbitals as the H₂ and LiH bonds are broken and we consider the orbital description of the H₂ + D ⇌ H + HD and LiH + H ⇌ Li + H₂ exchange reactions. We find that this orbital description leads to simple concepts in terms of which the changes in the system during reaction can be understood. It is expected that these concepts will apply to a large number of reactions.