Oxygen adatom diffusion on the NiO(001) surface by molecular dynamics simulation

We present results concerning the diffusion processes of O2- adatom on the NiO(0 0 1) surface obtained by molecular dynamics simulations based on a rigid ion potential model. We covered a temperature region from 0.37T(m) up to 0.71 T-m , T-m. being the melting point of the model system. It came out that the energetically favoured adatom position is located at the hollow site of the Ni sublattice. From the detailed analysis of the ionic trajectories, we found that the adatom diffuses via simple hopping and multiple exchange mechanisms. All processes exhibit Arrhenius behaviour from where we deduced the corresponding migration energies. Moreover, we found that although the frequency rates for hopping and exchange are comparable, the participation of the latter to the total diffusion coefficient is more important than that of hopping, by as much as an order of magnitude at high temperatures. (C) 2002 Elsevier Science B.V. All rights reserved