Ionization Energies of Acridine, Phenazine, and Diazaphenanthrenes

Ab initio electron propagator calculations on the lowest vertical ionization energies of acridine, phenazine, and five diazaphenanthrene isomers have been performed with the partial third order and outer valence Green's function approximations of electron propagator theory. Agreement with photoelectron spectra is very close, enabling the clarification of previous assignments. Numerous misorderings of final states from Koopmans's theorem are revealed. With the present approximations, Feynman−Dyson amplitudes are equivalent to canonical molecular orbitals. Plots of these one-electron functions aid in the interpretation of the spectra by revealing patterns of localization. Many final-state holes exhibit considerable mixing between nitrogen, lone-pair hybrids, and σ-bonding lobes.