Correlated one- and two-electron densities of low-lying S-states in helium-like atoms

Abstract

From high-quality, Pekeris-type electronic wavefunctions we calculate the single-particle density rho (r) and the intracule density h(s) of some low-lying S-states of two-electron atoms, obtaining very accurate values for the energies, the cusp-condition ratios and some radial expectation values. The effect of electron correlation on both densities for these states is also Studied by comparison with Hartree-Fock results. Some local important differences appear not only for the ground state, but also for the excited ones. Our results agree with some features previously found, such as the non-monotonic decrease of rho (r) for the excited states. We also find that the Coulomb hole of singlet excited states is strongly dependent on the procedure used for the Hartree-Fock calculations.