An analysis of core effects on shape-consistent pseudopotentials.
Large core (seven-valence electrons) shape-consistent averaged relativistic pseudopotentials (AREP) including core effects have been derived for the halogen series (Cl,Br,I,At). The influence of core effects on the spin-orbit splitting of the halogen and alkali atoms is clearly demonstrated within an all-electron four-component atomic reference calculation by means of a perturbation analysis. In particular, it is shown that AREPs extracted at the Dirac-Coulomb-Fock level, which already include spin-orbit polarization effects, give excellent results for atomic spectroscopy and equilibrium distances of halogen dimers. We also show that in our approach the core effects, included by configuration interaction using the numerical GRASP code, are transferred to the averaged orbital one-electron energy, defined in a perturbational way. This leads to a modification of the extracted AREPs by core effects, which is illustrated by calculations of the first atomic excited states using these AREPs. These results support the validity of including core effects directly in the AREPs extracted in a shape-consistent scheme. The transferability to the atomic excited states as well as to the molecular case is also verified.
Fromager
Emmanuel
E
Laboratoire de Physique Quantique, I.R.S.A.M.C, Université Paul Sabatier and CNRS (UMR 5626), 118, route de Narbonne, 31062 Toulouse cedex, France.
Maron
Laurent
L
Teichteil
Christian
C
Heully
Jean-Louis
JL
Faegri
Knut
K
Dyall
Ken
K