A generalized formula for the energies of alternant molecular orbitals. I. Homonuclear molecules

Abstract

AbstractUsing the method of alternant molecular orbitals (AMO) it is shown that the energies ofAMO's (Ek), for any alternant homonuclear molecule having a singlet ground state, are connected with the energies of theMO's (ek) obtained by the conventional Hartree–Fock (HF) method by the formula\documentclass{article}\pagestyle{empty}\begin{document}$ E_{k\alpha (\beta )} = \pm \sqrt {\Delta ^2 + e_k ^2 } $\end{document}, where Δ is the correlation correction. The formula is applicable in the semiempiricalLCAOform used in the Pariser–Parr–Pople theory, by Hubbard's approximation of γ integrals.