An improved IOC-ω technique. Part 1.—Ionization potentials and electron affinities of some molecules

Abstract

An improved IOC-ω technique (inclusion of overlap charges in the ω-technique) is described for the study of the physico-chemical properties of aromatic systems. The variation of resonance integrals β_rs with bond length is introduced into the calculation by means of an iterative “self consistent β” procedure. Ionization potentials of some alternant and non-alternant hydrocarbons and heterocyclic molecules and electron affinities of some alternant hydrocarbons have been calculated and the values are in excellent agreement with values obtained with more elaborate methods as well as with experimental values.

The technique described, once parametrized to fit a given molecular property, e.g., ionization potential, gives satisfactory results when used to calculate other properties e.g., electron affinities, π-bond energies, heats of formation and resonance energies of different classes of compounds.