Intra- and inter-shell correlation effects in Li-like ions: Coulomb holes and their interpretation

Abstract

Electron correlation has been examined in detail within the K alpha K beta , K alpha L alpha and K beta L alpha shells in position space for a series of Li-like systems in their ground state (1s22s alpha )2S. This necessitated the partitioning of the two-particle space-spin density and was straightforward for the Hartree-Fock description. For the correlated density, a previously devised partitioning technique based on a many-electron representation of a CI wavefunction was employed. Using existing wavefunctions, Coulomb holes, partial Coulomb holes and several one- and two-particle expectation values, and their percentage changes due to correlation, were evaluated for the intra- and inter-electronic shells. Since 3<or=Z<or=8, it was possible to examine the Z-dependent trends of the radial and angular components of electron correlation for each shell. The presence or otherwise of Fermi correlation in the inter-shell descriptions had a marked influence on their Coulomb correlation characteristics. The findings for the Li-like intra- and inter-shells were compared both with a previous analysis of the He-like and Be-like series of ions and also with a similar examination of the 21S and 23S excited states of He.