Journal of Chemical Physics vol:94 issue:4 pages:2928-2939
We describe fully relativistic calculations for the actinide tetrahalides UF4, ThF4, UCl4, and ThCl4 using the Dirac-Slater local-density model. We use an extended basis set of numerical atomic functions calculated in a potential well. A multipolar expansion technique is used to represent detailed features of the molecular charge density and the local exchange potential used is the Von Barth-Hedin-Lundqvist potential. By describing the molecules with physically reasonable wave functions and charge densities, we are able to calculate transition-state energies in good agreement with most features of the experimental photoelectron spectra. For the chlorine 3s levels we suggest revised ionization energies in the gas phase. The experimental values in the literature seem to have been incorrectly assigned, probably because they occur near the high energy limit for He(I) radiation.