Jumps and concerted moves in Cu, Ag, and Au(110) adatom self-diffusion

We present a molecular-dynamics simulation of self-diffusion on the (110) s urfaces of Cu, Ag, and Au. The metals are modeled by semiempirical potentia ls developed in the framework of the second-moment approximation to the tig ht-binding model. The energy barriers for the releyant diffusion processes are calculated by quenched molecular dynamics and compared with the availab le data in literature, obtaining a good agreement. The occurrence of long j umps is investigated in detail, showing that the three metals behave quite differently with this respect: long jumps are practically absent in Au and frequent in Cu. The effect of the specific features of the potential-energy surface and of the energy dissipation to the substrate on the probability of long jumps is investigated. The Arrhenius behavior of the jump rate is d iscussed, and deviations are found at high temperatures. Concerning correla ted jump-exchange processes and double exchanges, we find that they are com mon in Cu even at rather low temperatures, whereas they are never observed in Au, Ag showing an intermediate behavior. [S0163-1829(99)01808-1].