SELF-DIFFUSION PROCESSES OF COPPER ADATOM ON CU(110) SURFACE BY MOLECULAR-DYNAMICS SIMULATIONS

The self-diffusion mechanisms of single adatoms on the Cu(110) surface have been studied using molecular dynamics simulation and a many-body potential within the second-moment approximation of the tight-binding model. From a detail trajectory analysis we found a variety of diffus ion mechanisms, the hopping being the favoured one and we deduced the migration energies for the most important among them. At high temperat ures, saturation in diffusion frequency for both hopping and exchange mechanisms is observed, indicating that the diffusion proceeds via com plicated and concerted movements. In addition, we estimated the format ion energy for the spontaneous creation of the vacancy-adatom pair, in good agreement with the experiment. Furthermore, from the temperature dependence of the relaxed adatom positions we found that the adatom e xhibits strong contraction compared to the bulk interlayer spacing, at taining -20% at high temperatures. (C) 1998 Elsevier Science Ltd. All rights reserved.