The generalized parameterization procedure for the semiempirical MO method and calculation of ionization potentials for the third row element molecules

Abstract

The valence electron ionization potentials ( I l ) were collected from a unique resource for the elements from H to Xe. The electron affinities ( A 1) of halogen atoms in each period were obtained from the same resource of I l . The A l values of the remaining elements were obtained by a combined formulation of Slater-Condon integrals and Pariser-Parr approximation. The generalized bond parameter proportionality constant K nl of each period was also evaluated. Using these parameters, twenty-four molecules consisting of only third row elements were selected for the s-p-d INDO-MO calculations. In order to check the reliability of the energy calculations, similar calculations of ab initio type STO-3G ∗, along with semiempirical-type PM3 and AM1 methods were also carried out for comparison. The Koopmans' theorem was applied to compare the experimentally measurement and calculation of the first ionization potentials in all the cases. The results of the present study indicated that the s-p-d INDO MO computed with the new parameterization procedure which given here is the best method among all the methods used in the present work.