Coulomb correlation in the 21S, 23S, 21P and 23P states of He

Publisher Website
Google Scholar
Abstract
Electron correlation has been examined in detail for the 21S, 23S, 21P and 23P states of He and comparisons are made with the ground state. The correlated and Hartree-Fock descriptions of these (1s, nl) excited states are provided by the wavefunctions of Tweed (1973) and Davidson (1965), respectively. Coulomb holes, various partial Coulomb holes and several one- and two-particle expectation values are presented. The concept of partial Coulomb holes and their collective presentation has surfaces as been demonstrated to be particularly informative. These surfaces enabled us to interpret correlation effects in different regions of space and so provide a rationalisation of the correlation mechanisms in each state. For all four states, correlation caused a significant inward shift of density from the outer regions due to a reduction in nuclear shielding. However, in the inner regions around the nucleus, the influence of correlation was more complicated and depended not only on the multiplicity of the state but also on its symmetry.