Charge densities and two-electron intracules for the low-lying excited states of the helium-like ions

Abstract

Spherically averaged one-electron charge densities rho (r) and two-electron intracule functions h(u) are computed for the 23S, 21S, 23P and 21P states of the helium-like ions from He to Mg10+. The distributions, based on correlated wavefunctions containing explicit dependence on the interelectronic separation, are expected to be the most accurate ones available. Interesting qualitative results obtained from a graphical analysis include the non-monotonicity of rho (r) in the 21S states of He, Li+ and Be2+, the absence of shell structure in the radial charge densities D(r) of the 23P and 21P states of the highly charged ions, and the absence of an intra-K-shell maximum in the radial intracule densities P(u) for the 21P states.