MOLECULAR PHOTOIONIZATION CROSS-SECTIONS BY THE LOCAL-DENSITY LCAO STIELTJES IMAGING APPROACH

Valence partial photoionization cross sections relative to N-2, CO2, N 2O, C2N2, SF6, TiCl4 and Cr(CO)6 are evaluated at the local density le vel. The muffin-tin potential approximation is avoided by the use of l arge basis set LCAO calculations and the Stieltjes imaging approach. C omparison with experimental data and accurate ab initio calculations i n the smaller systems proves the reliability of the approach, which fu rnishes results comparable to the ab initio ones at the Hartree-Fock l evel. Significant improvement over comparable MS-X alpha calculations is obtained for the linear systems, notably the removal of spurious re sonances. Notably the computational effort does not increase inordinat ely in the larger systems, where convergence in the moment expansion i s even better, owing to the increased basis set size. The technique ap pears valuable in extracting information and assisting interpretation of experimental cross sections in complex systems, and as an aid to th e resolution of assignment problems.