Correlation and Self-Repulsion in Studies of Molecular Ions with the Ham Method

Abstract

In the study of positive and negative molecular ions the primary data can be said to be the energies which are required to produce them from the molecules. The ionization energies are usually calculated using Koopmans’ theorem, which means, that the accuracy depends upon the extent to which the correlation energy change and the reorganization energy cancel each other. For electron affinities there is no such cancellation, and the calculation of electron affinities is therefore difficult and only few such studies have been published.