VACANCY GENERATION AND ADSORPTION OF Cu ATOM AT Ag(1 1 1) SURFACE DURING DIFFUSION OF Cu-TRIMER

Abstract

In this paper, the vacancy generation at (1 1 1) surface of silver ( Ag ) and the adsorption of copper ( Cu ) atom in the vacant site at Ag (1 1 1) surface has been studied using molecular dynamics (MD) simulation technique. The run of micro-canonical constant energy (NVE) ensemble results the generation of vacancy at 700 K in the presence of Cu -trimer, and its migration is observed toward the island as a result of self-diffusion of the surface layer atom. The energy of vacancy generation at Ag surface is found to be Ev = 1.078 eV , in the presence of Cu -trimer. The popped-up Ag adatom combines with Cu -trimer, making a mixed-tetramer ( Cu 3– Ag island). The adsorption energy of the Cu -atom among the mixed-tetramer island into the substitutional site is Es = ~ -0.813 eV , leaving a mixed-trimer ( Cu 2– Ag island) at Ag (1 1 1). Moreover, the presence of the island creates some anharmonic effects like dislocations and fissures at the surface. These dislocations and fissures show a trend of attraction to each other and also migrate toward the island, during the time evolution of the system.