The hopping self-diffusion coefficient of an adatom on the (100), (110) and (111) surfaces of face-centered cubic metals (Ag, Al, Au, Cu, Ir, Ni, Pd, Pt, Rh) was investigated by using Monte Carlo variational transition state theory and Lennard-Jones interactions. The potential parameters for Lennard-Jones interactions were determined from known experimental values of the cohesive energies and lattice constants. The ratio of the cohesive energy to the activation energy, for diffusive hopping on the (111) and (100) surfaces, was found to be 30 and 6, respectively. For diffusive hopping on the (110) surface, the ratio depended upon the direction of diffusion: the ratio was 5 and 2.8 along the [1¯10] and [001] directions, respectively. The pre-exponential factor for the metals was found to vary, within a factor of 3, from the corresponding average value for a given surface and diffusion channel. The pre-exponential factors which corresponded to diffusion on the (111), (100), (110)[1¯10] and (110)[001] surfaces were found to satisfy an empirical expression in terms of the ratio of cohesive energies, the lattice constant and the distance between the 2 nearest binding sites.

Predicting Trends in Rate Parameters for Self-Diffusion on FCC Metal Surfaces. P.M.Agrawal, B.M.Rice, D.L.Thompson: Surface Science, 2002, 515[1], 21-35