Ab initio interatomic potentials for low-energy He ion/atom scattering

Ab initio (density functional theory) binary interatomic potentials have been calculated for low-energy He projectile interactions with target atoms having atomic numbers (Z(2)) from 6 to 54 (C to Xe). The calculated potentials cover the energy range that is typical for low-energy ion He ion/atom-scattering spectroscopy (<= 2-7 keV, depending on Z(2)). For constant R, the screening function exhibits Z(2) oscillations that are indicative of the electronic stabilities of the corresponding quasi-molecules; screening function minima are observed for the quasi-molecules that are isoelectronic with the noble gases. The He-Z(2) interatomic potentials calculated for target elements lighter than Rb are suitable for use in simulations of low-energy ion-scattering experiments. However, the potentials calculated for target atoms heavier than Kr do not offer any clear benefits over the existing empirical potentials. The solid-state potential shift applicable to scattering in metallic solids has been estimated as typically 0 to + 10 eV, using a simple thermodynamic model that exploits the similarities between the valence states of an He-Z(2) quasi-molecule and the corresponding united atom.