Theoretical study of the photoelectron spectra of gaseous Cu₃Cl₃

Ab initio calculations have been performed to interpret the photoelectron spectrum of gaseous cuprous chloride, Cu3Cl3. Density functional calculations revealed Cu3Cl3 to be a planar cyclic D3h molecule. Koopmans' theorem and two-hole/one-particle calculations with canonical Hartree-Fock orbitals were used to interpret the vertical ionization energies. These were compared with similar calculations using B3LYP Kohn-Sham orbitals. The results confirm the claim by Casida that Kohn-Sham orbitals mimic Dyson orbitals.