Dynamical Behaviour of Ag and Cu Double-Layer Islands on fcc(111), Surfaces

Abstract

Molecular dynamics simulations are preformed to investigate thediffusion behaviour of Ag/Cu double-layer islands on Ag(111)/Cu(111)surfaces, showing that atoms of the top island usually diffuse into thelower island by exchange mechanism when they move to the verge of thelower island via a concerted motion. Compared to the Cu adatoms, the Agadatoms can easily form a kind of stable compact cluster of hexagonalisland during their diffusion processes, and this cluster make itpossible that the decay rate of the top Ag island is considerablyslower than that of the Cu island. In addition, we find that theexchange mechanism is predominant compared to the jumping process inthe simple potential calculation. These simulation results are inagreement with previous experimental observations and theoreticalcalculations.