The Electronic Spectra of Aromatic Molecules II: A Theoretical Treatment of Excited States of Alternant Hydrocarbon Molecules based on Self-Consistent Molecular Orbitals

The theoretical treatment of the electronic spectrum of benzenoid hydrocarbons recently given by Dewar and Longuet-Higgins (Part I) is generalized so that full account is taken of electron interaction. The method is based on the use of a self-consistent molecular orbital function for the ground state and corresponding functions for excited states. It is found that all the general features of the method of Part I carry over, although certain accidental degeneracies are removed. Approximate numerical calculations based on the new method give support to the assignments made by Dewar and Longuet-Higgins.