Multiconfiguration Hartree-Fock calculation of photoionization cross sections of the rare gases. II. Final-state correlation

Cross sections and angular distributions for the photoionization of the rare gases have been calculated using a modified Hartree-Fock equation for the continuum orbital and a multiconfiguration Hartree-Fock description of the ground state. The modification of the Hartree-Fock equation for the continuum orbital is produced by virtual pair excitations of the ionic core analogous to those incorporated in the ground state. The modification reduces to the addition of two terms to the standard $V^{N-1\mathrm{}\left(\mathrm{LS}\right)\mathrm{}}$ potential when small terms are neglected. The addition of this final-state correlation effect gives improved agreement with experimental cross sections as compared to a previous calculation which included only ground-state correlation effects.