Simulation of dimer diffusion on metal fcc (001) surfaces by molecular dynamics

We study systematically the dimer diffusion on metal fcc (001) surfaces through molecular dynamics calculations based on embedded atom method. Besides the conventional hopping and exchange mechanisms, some other interesting diffusion mechanisms are observed, such as the exchange rotation mechanism, the cooperative hopping mechanism, and the cooperative exchange mechanism. On the different kinds of metal surfaces, we find that not only the dominant diffusion mechanism but also the physical model for the exchange mechanism is different.