Electronic Interaction in the Free-Electron Network Model for Conjugated Systems. I. Theory

The free-electron network model for conjugated systems is extended to include electronic interaction. The free-electron wave functions are considered as molecular orbitals arising from an average one-electron potential, and a configuration interaction treatment with these MO's is developed. The integrals occurring in this procedure, in particular the electron interaction integrals, are analyzed and a convenient method for their computation in the FE model is suggested. The integral evaluation requires certain semiempirical parameters which are determined from the benzene spectrum.