The motion of adatoms on a face-centred cubic(111) surface was modelled. In the light of recently revealed specific features of the potential energy surface, a new empirical potential which took account of the non-equivalence of face-centred cubic and hexagonal close-packed adsorption sites was proposed. The modelling was performed by using the method of stochastic cycles, a new variety of MDM. Calculations were performed for the diffusion of oxygen atoms over a platinum surface. The potential energy surface was constructed based upon experimental data and DFT calculations. A analysis demonstrated that the diffusion activation energy coincided with the static barrier while the pre-exponential factor was weakly temperature-dependent. However, the degree of asymmetry of the potential produced a significant effect upon the pre-exponential factor: the change-over from a symmetrical two-well potential to a strongly asymmetrical single-well potential caused an increase in the pre-exponential factor by an order of magnitude.

Diffusion of Atoms on an FCC(111) Surface. A.S.Prostnev, B.R.Shub: Russian Journal of Physical Chemistry B, 2008, 2[5], 502-6