Model studies of atom and molecule diffusion on surfaces

We report a classical trajectory study of the diffusive dynamics of a rigid-rotor N2 trapped on a rigid but corrugated LiF(001) surface. An analogous study is also made for a fictitious atom with the atomic weight of N2. The ensemble-averaged square displacement as well as the velocity autocorrelation functions are computed for a range of kinetic energies, each exhibiting the standard signatures for diffusive behavior. The ‘‘temperature’’ dependence of the diffusion coefficients determined show Arrhenius behavior with an activation energy which can be approximately related to barriers on the three-dimensional potential surface.