Numerical study of hetero-adsorption and diffusion on (100) and (110) surfaces of Cu, Ag and Au

Quenched molecular dynamics simulations and density-functional theory (DFT) calculations are used to study the adatom hetero-diffusion on the (100) and (110) surfaces of four systems: Au/Ag, Ag/Au, Au/Cu, Cu/Au. Atomic interactions are described by embedded-atom method potentials, that are validated by a comparison with DFT results on diffusion barriers. The local relaxation of surface atoms around the adatom is analyzed, together with adsorption energies and hopping diffusion barriers. We find that atomic relaxation is qualitatively different between (100) and (110) surfaces, with the exception of the Au/Cu case. Hopping diffusion barriers are larger on the (100) than on the (110) surface. Many-body and relaxation effects cause significant differences between Ag/Au and Au/Ag barriers, and between Cu/Au and Au/Cu barriers.