MOLECULAR-DYNAMICS STUDY OF SELF-DIFFUSION - IRIDIUM DIMERS ON IRIDIUM SURFACES

Using a molecular-dynamics simulation, we have investigated the mechan isms of single dimer self-diffusion on the (111), (001), and (110) sur faces of fcc iridium. We use a realistic many-body potential, namely, the Rosato-Guillope-Legrand model potential, which involves empirical fittings of bulk properties of the solid. On the (001) and (110) surfa ces, evidence of atomic diffusion by exchange mechanisms of the dimer atoms with substrate atoms are found. This is in good agreement with f ield-ion microscope observations. In addition, a preliminary investiga tion of the mechanisms of self-diffusion of iridium trimer on the (110 ) plane has also been carried out.