The rate of diffusion of Cu adatoms on the Cu(100) surface was calculated by using thermodynamic integration within transition-state theory. The results were found to be in excellent agreement with the essentially exact values which resulted from molecular-dynamics simulations. The activation energy and related entropy were shown to be effectively independent of temperature, thus establishing the validity of the Arrhenius law over a wide range of temperatures. It was concluded that the perfect agreement of the present results, and molecular dynamics results, clearly demonstrated that a simple representation of the diffusion rate in terms of a static energy barrier (which defined the activation term) and a temperature-independent entropy (which defined the pre-factor) accounted fully for the dynamics of isolated adatoms.

Surface Diffusion Coefficients by Thermodynamic Integration: Cu on Cu(100). G.Boisvert, N.Mousseau, L.J.Lewis: Physical Review B, 1998, 58[19], 12667-70