Self-Consistent Polarization Propagator Calculations in the Pariser-Parr-Pople Model. A Modified Random Phase Method

Abstract

By decoupling the equation of motion for the two‐particle Green's function, a self‐consistent scheme for describing particle‐hole excitations is developed. The self‐consistent propagator is brought into a form which easily yields excitation energies and oscillator strengths. The method is applied to the π‐electron systems of ethylene, butadiene, and benzene. Comparison is made with results obtained in the time‐dependent Hartree‐Fock approximation and related schemes. The problems concerning particle number conservation in these methods are discussed.