Calculated Pre-exponential Factors and Energetics for Adatom Hopping on   Terraces and Steps of Cu(100) and Cu(110)
  We have calculated the vibrational dynamics and thermodynamics for Cu adatom hopping on terraces and near step edges on Cu(100) and Cu(110), using the embedded atom method for the interatomic potential. The local vibrational densities of states were calculated using real space Green's function formalism and the thermodynamical functions were evaluated in the harmonic approximation. The calculated diffusion energy barriers for six specific local environments on Cu(100) agree well with experimental and previous theoretical results. Contribution of vibrational entropy to the change in the free energy of the system as the adatom moves from the equilibrium configuration (hollow site) to the saddle point, is found to be as much as 55meV (144 meV) at 300K (600K). The prefactors for all 13 cases are found to be of the order of 10-3 cm2/s, almost independent of temperature, and the respective activation energy barriers. 
Handan Yildirim, Abdelkader Kara, Sondan Durukanoglu, Talat S. Rahman