Simulation of vacancy diffusion in a silver nanocluster

Abstract

► In a Ag nanocluster, vacancy dynamics is much faster than in extended systems. ► The energetically preferred site of the vacancy is vertex > subsurface > compact surface. ► Vacancy formation and diffusion represents the preferred path for atom–atom exchange. The formation and diffusion of a vacancy in a silver nanocluster are studied via a combination of first-principles and statistical mechanics simulations. A 38-atom truncated-octahedral (TO) arrangement and its homologue with 37 Ag atoms and one vacancy are considered, and density-functional calculations are performed to derive the energies of the local minima and the energy barriers connecting them. These data are then used as an input for a study of the system dynamics via a kinetic Monte Carlo algorithm, evaluating site occupancies, diffusion coefficient and equilibration time. It is found that vacancy formation and diffusion represents a viable path for atom–atom exchange in these conditions.