A potential for simulating the atomic assembly of cubic elements

Molecular dynamics simulations using Stillinger-Weber potentials have been widely used to study the growth of diamond-cubic materials since these potentials are easily parameterized to ensure that the diamond-cubic structure has the lowest cohesive energy. However, Stillinger-Weber potentials can only be used to model cubic crystals with the diamond-cubic structure. Here we generalize the Stillinger-Weber potential formulism and explore its application to other cubic crystal structures. Parameterization of this modified Stillinger-Weber potential is exemplified by developing potentials for four elements: Si (diamond-cubic), Ni (face-centered-cubic), Fe (body-centered-cubic), and Po (simple-cubic). The parameterized potentials predict well the cohesive energy and lattice constants of each element. Molecular dynamics simulations are used to test the ability of the potentials to simulate the crystalline assembly of these materials from their atomic vapor. Defects are found in the films grown under kinetically constrained conditions.