MICROSCOPIC THEORY AND SIMULATION OF ADATOM DIFFUSION ON IR(111)

Using a realistic tight-binding Hamiltonian we have calculated the eff ective cluster interactions that describe the ordering of adsorbed Ir atoms on the Ir(111) surface. We have determined the relative stabilit y of adatoms in ''bulk'' and ''surface'' sites and also mapped out the barrier between them. This information is then used as input in Monte Carlo simulations which allow us to determine typical diffusion behav ior at various temperatures.