Break-down of the molecular-orbital picture of ionization: CS, PN and P₂

Ionisation potentials and spectral intensities for photoionisation of the valence electrons of CS, PN and P₂ have been calculated applying the so-called 2ph-TDA method (see ibid., vol.11, no.11, p.1889, 1978). Strong correlation effects are found for the two inner-most valence orbitals of all these species, showing that the independent-particle picture of ionisation fails completely. As far as available the results are compared to experimental data and to Green's function calculations previously performed for the outer valence orbitals.