Interatomic potential for the Cu-Ta system and its application to surface wetting and dewetting

Abstract

An angle-dependent interatomic potential has been developed for the Cu-Ta system by crossing two existing potentials for pure Cu and Ta. The cross-interaction functions have been fitted to first-principles data generated in this work. The potential has been extensively tested against first-principles energies not included in the fitting database and applied to molecular dynamics simulations of wetting and dewetting of Cu on Ta. We find that a Cu film placed on a Ta (110) surface dewets from it, forming a Cu droplet on top of a stable Cu monolayer. We also observe that a drop of liquid Cu placed on a clean Ta (110) surface spreads over it as a stable monolayer, while the extra Cu atoms remain in the drop. The stability of a Cu monolayer and instability of thicker Cu films are consistent with recent experiments and first-principles calculations. This agreement demonstrates the utility of the potential for atomistic simulations of Cu-Ta interfaces.