SCF—MO—LCAO—CI Treatment of the Pi-Electronic Structure of Formaldehyde Using Ohno's Formula for βCO and Constrained to Satisfy Koopmans' Theorem Exactly

Abstract

The Pople—Pariser—Parr simplification of Roothaan's matrix formulation of the Hartree—Fock self-consistent-field (SCF) equations is applied to the pi-electronic portion of the formaldehyde molecule as (1) a test of the use of Ohno's resonance integral formula as a basis for obtaining self-consistent resonance integrals for heterobonds and (2) as a test of the effect of constraining the energy of the highest occupied orbital to satisfy Koopman's theorem exactly. The calculated spectroscopic intervals, dipole moments, and charge distributions are not too far different from those obtained by the self-consistent-electronegativity method of Brown and Heffernan, but there are indications that the present method may form a more satisfactory basis for extension to other heteroatomic conjugated systems.