CORRELATED ONE-ELECTRON AND 2-ELECTRON DENSITIES OF LOW-LYING S-STATES IN HELIUM-LIKE ATOMS

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