Cluster expansion of the wavefunction. Ionization potentilals of benzene

The vertical and adiabatic ionization potentiais of benzene are studied by the cluster expansion of the wavefunction theory. The calculation confirms the assignment of the photoelectron spectrum experimentally proposed by Jonsson and Lindholm. The nature of the Jahn-Teller effect in states arising from ionization of doubly degenerate π and σ orbitals is also discussed.