Configuration Interaction in Molecular-Orbital Theory

Abstract

The importance of configuration interaction within the framework of a Pariser‐Parr treatment of π systems is reviewed and further studied. Three molecules—octatetraene, styrene, and naphthalene—are considered in detail. The energies obtained for the various states are shown to be often quite dependent upon the number of configurations included. Finally, it is argued that, if molecular‐orbital configuration interaction is to be of predictive value over a wide range of compounds, then the best general criterion for inclusion of a configuration should be its energy, and that the cutoff point should not be less than 20 eV.