High-Temperature Simulation of Diffusion of Ag on Ag(110)

Abstract

The high-temperature diffusion of silver adatoms on Ag(110) is studied by molecular dynamics simulations. Silver is modeled by many-body potentials derived in the framework of the second-moment approximation to the tight-binding model. Single and long jumps along the [110] direction and cross-channel exchanges are found at the lowest temperature considered in the simulations (450 K); simple exchanges are possible along the [001] direction and in the diagonal direction, essentially with the same probability. Correlated events involving both jumps and exchanges become important as the temperature is raised to 600K. These events can be jump-exchange, exchange-jump, exchange-exchange, or even more complicated and, above 600 K, they amount to about one-quarter of the total exchanges. The appearance of these events is related to the strong anharmonic vibrations of the row atoms in the top surface layer.