Variable charge simulations were to study the diffusion mechanisms of oxygen atoms in nickel at 950 to 1600K and the very first steps of oxidation of monocrystalline nickel surfaces at 300 and 950K. The oxygen diffusivity could be well described by an Arrhenius law over the temperature range considered. The oxygen diffusion coefficient was analysed and values of Ea = 1.99eV for the activation energy and D0 = 39cm2/s for the pre-exponential factor were obtained. The first steps growth of the oxide layer showed that, after dissociative chemisorption of the oxygen molecules on nickel surfaces, the oxidation led to an island growth mode as observed experimentally.

Numerical Studies of the Diffusion Processes and First Step Oxidation in Nickel-Oxygen Systems by Variable Charge Molecular Dynamics. Garruchet, S., Politano, O., Arnoux, P., Vignal, V.: Defect and Diffusion Forum, 2010, 297-301, 513-8