Calculated Pre-exponential Factors and Energetics for Adatom Hopping on Terraces and Steps of Cu(100) and Cu(110)

摘要

We have calculated the vibrational dynamics and thermodynamics for Cu adatomhopping on terraces and near step edges on Cu(100) and Cu(110), using theembedded atom method for the interatomic potential. The local vibrationaldensities of states were calculated using real space Green's function formalismand the thermodynamical functions were evaluated in the harmonic approximation.The calculated diffusion energy barriers for six specific local environments onCu(100) agree well with experimental and previous theoretical results.Contribution of vibrational entropy to the change in the free energy of thesystem as the adatom moves from the equilibrium configuration (hollow site) tothe saddle point, is found to be as much as 55meV (144 meV) at 300K (600K). Theprefactors for all 13 cases are found to be of the order of 10-3 cm2/s, almostindependent of temperature, and the respective activation energy barriers.