Cu dimer diffusion energy barrier on strained Cu(001) surfaces was studied with nudged elastic band method (NEB) and embedded atom method. Dimer exchange and hopping mechanisms were chosen as the initial diffusion paths in the NEB method. It was shown here that the dimer exchange was dominant on tensile surfaces and the dimer hopping was dominant on compressive surfaces. For most strain conditions Cu dimer diffusion energy barrier was lower than Cu monomer diffusion barrier. The concerted movement of the remaining adatom toward the hopping adatom lowers the dimer hopping barrier. The adsorption induced relaxation makes the dimer exchange barriers lower than the monomer exchange barriers on tensile surfaces. Transition state theory was used to calculate the diffusion frequencies as a function of temperature. No surface crowdion was observed on the shear strained surfaces for the dimer diffusion.

Cu Dimer Diffusion on Strained Cu(001). Z.Duan, W.Xiao: Surface Science, 2010, 604[3-4], 337-45