Electronic structures of the bound excited quartet states of the helium anion

The radial and electron-pair density functions of two bound excited states of the helium anion have been calculated at the full configuration-interact ion level with an extended basis set. It is shown that the form of the radi al density in the (1s2s2p)P-4 and (2p(3))S-4 states of He- is readily inter preted in terms of orbital contributions, even at the full configuration le vel at which level of theory the notion of an electronic configuration lose s its precise meaning. The smaller radial distance of the L-shell maximum i n the 4S State relative to the lower-lying P-4 state is interpreted in term s of a higher effective nuclear charge in the 4S state. The more compact el ectron cloud of the 4S State leads to a narrower intracule density than tha t observed for the P-4 state. The 4S state is shown to have a Coulomb hole with the same classic form as the ground state of helium but with a radius that is about six times larger. The depth of the Coulomb hole is substantia lly greater in the 4S state than in the 4P state, as expected from the fact that the correlation energy is greater in the former state. The Coulomb ho les of both states exhibit a vanishingly small depth at small interelectron ic distances due to the presence of the Fermi hole. [S1050-2947(99)00612-5] .