The diffusion of a dimer along the trough between dimer rows on the (001) surface was modelled by using density-functional theory. In spite of the fact that the lowest-energy pathway involved break-up of the dimer into adatoms, a statistical model showed that the dimer was likely to re-form just 1 or 2 sites along the trough. The energy barrier which was predicted was in very good agreement with recent experimental results.

C.M.Goringe, D.R.Bowler: Physical Review B, 1997, 56[12], R7073-5