Ab initio  static relaxation methods and semi-empirical molecular dynamics simulations were used to investigate the energetics and dynamics of the diffusion of adatoms, dimers, and vacancies on (100) surfaces. It was found that the dynamic energy barriers to diffusion were well-approximated by static 0K barriers, and that the pre-factors did not depend sensitively upon the species which was diffusing. The  ab initio  barriers were seen to be significantly lower when calculated within the generalized-gradient approximation than within the local-density approximation. The calculations predicted that surface diffusion should occur mainly via the diffusion of vacancies. The adatoms were found to migrate most easily via a jump mechanism. This was also true of dimers, even though the corresponding barrier was slightly higher than it was for adatoms. It was further observed that dimers diffused more readily than they dissociated.

Self-Diffusion of Adatoms, Dimers and Vacancies on Cu (100) G.Boisvert, L.J.Lewis: Physical Review B, 1997, 56[12], 7643-55