MODEL POTENTIALS FOR MAIN-GROUP ELEMENTS LI THROUGH RN

Model potential (MP) parameters and valence basis sets were systematic ally determined for the main group elements Li through Rn, For alkali and alkaline-earth metal atoms, the outermost core (n - 1)p electrons were treated explicitly together with the ns valence electrons. For th e remaining atoms, only the valence ns and np electrons were treated e xplicitly. The major relativistic effects at the level of Cowan and Gr iffin's quasi-relativistic Hartree-Fock method (QRHF) were incorporate d in the MPs for all atoms heavier than Kr. The valence orbitals thus obtained have inner nodal structure. The reliability of the MP method was tested in calculations for X-, X, and X+ (X = Br, I, and At) at th e SCF level and the results were compared with the corresponding value s given by the numerical HF (or QRHF) calculations. Calculations that include electron correlation were done for X-, X, and X+ (X = Cl and B r) at the SCDI level for AS(2) at the CASSCF and MRSDCI levels. These results were compared with those of all-electron (AE) calculations usi ng the well-tempered basis sets. Close agreement between the MP and AE results was obtained at all levels of the treatment. (C) 1997 America n Institute of Physics.