Ground-state potential curves for Al2 and Al2/ts6+/ in the repulsive region

Self-consistent-field (SCF) calculations have been performed for the short-range interaction between two aluminum atoms. The ground-state potential curve (3Σ-/sub g/→5Σ-/sub u/→3Σ+/sub u/→1Σ+/sub g/ →3Pi/sub g/) is presented for internuclear separations between R/sub e/ and 0.1 a.u. (repulsive energies up to approx.103 a.u.). Basis sets consist of scaled even-tempered Slater orbitals of double-zeta quality, augmented by diffuse functions, with the addition of united or semiunited atom-basis sets centered on the bond. The SCF potentials are compared with Thomas-Fermi theory and with the electron-gas calculations of Wilson, Haggmark, and Biersack. A kink in the SCF screening function is found near R=2 a.u. This feature is believed related to changes in the ground-state configuration that occur in this region. Additional calculations (SCF and linear combination of atomic orbitals were performed on Al2/ts6+/ to determine individually the core overlap and the valence-electron contributions to the interatomic potential. The core-overlap interaction is compared with Gordon-Kim electron-gas calculations. Schematic calculations were also performed on the Al-Al3+ system to estimate the interaction between an atom and an energetic ion