MOLECULAR PHOTOIONIZATION CROSS-SECTIONS BY THE LOBATTO TECHNIQUE .2.CORE-LEVEL PHOTOIONIZATION

The logarithmic derivative Kohn-Lobatto (LDKL) method for determining molecular electronic continuum wave functions is applied to the calcul ation of core level photoionization cross sections. The description of the photoionization process is based on a local effective potential o btained from density functional theory. However, the LDKL method avoid s a shape approximation to the potential like the muffin-tin form unde rlying the continuum multiple scattering (CMS) method. Different from the procedure for the investigation of valence photoionization the inf luence of the attractive hole has to be taken into account explicitly. Slater's transition state potential in the local density approximatio n (LDA) leads to very satisfactory predictions of photoionization cros s sections and asymmetry parameters. This is demonstrated for the well known cases of N2 and CO. Applications to the inner shell photoioniza tion of SF6 illustrate that the LDKL method in the present LDA impleme ntation affords an efficient and accurate treatment of larger molecule s for which it offers an alternative superior to the widely used CMS-X alpha method.