Hetero-diffusion of small clusters on Ag(111) surface

The investigation reported in this paper is an attempt to analyze and understand the hetero-diffusion of small clusters on the (111) surface of Ag. This work has been realized using molecular statics simulations based on semi-empirical many body potentials described by the embedded atom method. For this study, we have considered three heterogeneous systems Cu_n/Ag(111), Ag_n/Ag(111) and Au_n/Ag(111), where n is the number of cluster atoms (n = 1 , 2, 3, 4 or 5). Our findings show that the clusters diffuse on the (111) surface via two different diffusion processes, namely the zigzag motion and the concerted jump. Moreover, the activation energy increases from adatom, dimer, to trimer, and goes down at tetramer, and then rises again for pentamer. This behavior is similar for the three systems under study and also to the one obtained by the density-functional theory for the homogenous systems.