Dynamics of oxidation of aluminum nanoclusters using variable charge molecular-dynamics simulations on parallel computers

Oxidation of aluminum nanoclusters is investigated with a parallel molecular-dynamics approach based on dynamic charge transfer among atoms. Structural and dynamic correlations reveal that significant charge transfer gives rise to large negative pressure in the oxide which dominates the positive pressure due to steric forces. As a result, aluminum moves outward and oxygen moves towards the interior of the cluster with the aluminum diffusivity 60% higher than that of oxygen. A stable 40 A thick amorphous oxide is formed; this is in excellent agreement with experiments. [S0031-9007(99)09416-8].