Scattered-wave calculations of photoionization cross-sections and asymmetry parameters for CO, H2O and H2S

Partial photoionization cross-sections and asymmetry parameters are calculated for the valence orbitals of the molecules CO, H2O, and H2S and of the atoms O and S using a recently developed extension of the self-consistent field-Xα-scattered-wave method to continuum states. The convergence of the partial-wave expansions for both initial and final states is studied for electron kinetic energies in the range 2-1000 eV. Since convergence is very slow at high kinetic energies, the interesting region between 2 and 50 eV is emphasized, and comparisons are made with experimental UV photoemission results where such data are available. Overall the method appears to be far more reliable than previous calculations for polyatomic molecules which have used plane-wave or orthogonalized plane-wave or orthogonalized plane-wave final states. (orig.)