It was recalled that the mechanism of surface migration was considered to be due to a competition between adatom energy relaxation and motion in the migration state above the activation energy. If relaxation were retarded, multiple-site hopping became noticeable. In other cases, a model which involved jumps into nearest-neighbor sites was valid. In order to calculate the jump probabilities, kinetic equations were used here in which convection was described in terms of particle exchange between adjacent surface cells. The latter assumption was justified by an efficient randomization of motion in the migration state, and was confirmed for the case of the body-centered cubic (110) face by means of numerical simulation. The corresponding rate constant was linear in energy in the most important region. The estimated jump probabilities, into second-nearest sites, for W self-diffusion on W(110) were equal to a few percent at room temperature, but exhibited a sensitive temperature dependence.

A.S.Prostnev, M.A.Kozhushner, B.R.Shub: Surface Science, 1995, 336, 385-96