A potential for simulating the atomic assembly of cubic AB compounds

Stillinger-Weber interatomic potentials can be used to study the crystal growth of AB compounds with the zinc-blende (B3) structure, but have been unable to be used for other cubic structured compounds. Here we extend a recently modified Stillinger-Weber potential for cubic elements so that it is suited for studying the growth of cubic compounds with the B1 and B2 structures. We also parameterize the potential for the Mg-O system. The potential is shown to accurately model the lattice constants and the cohesive energies of the fcc Mg, fcc O, and the B1 MgO structures. It also correctly ensures that the equilibrium phase of each of these materials possesses the lowest cohesive energy with respect to all their other phases. The potential correctly predicts crystalline growth during molecular dynamics simulations of the vapor deposition of fcc Mg and B1 MgO thin films. The results also reveal the formation of various defects in the films, including islands and twins in Mg, interstitials and disrupted regions on the MgO growth surface, and local un-oxidized regions at the MgO/Mg interface during the oxidation of Mg. The simulation approach enables the study of atomic assembly processes controlling the formation of these defects.