PARTIAL 3RD-ORDER QUASI-PARTICLE THEORY - COMPARISONS FOR CLOSED-SHELL IONIZATION ENERGIES AND AN APPLICATION TO THE BORAZINE PHOTOELECTRON-SPECTRUM

Valence ionization energies of a set closed-shell molecules calculated in a partial third-order (P3) quasiparticle approximation of the elec tron propagator have an average absolute error of 0.19 eV. Diagonal el ements of the self-energy matrix include all second-order and some thi rd-order self-energy diagrams. Because of its fifth power dependence o n basis set size and its independence from electron repulsion integral s with four virtual indices, this method has considerable potential fo r large molecules. Formal and computational comparisons with other ele ctron propagator techniques illustrate the advantages of the P3 proced ure. Additional applications to benzene and borazine display the effic acy of the P3 propagator in assigning photoelectron spectra. In the bo razine spectrum, (2)E' and (2)A'(2) final states are responsible for a n observed feature at 14.76 eV. Another peak at 17.47 eV is assigned t o a (2)E' final state. (C) 1996 American Institute of Physics.