The diffusion of Xe atoms, physisorbed on the Si(100)-2x1 surface at sub-monolayer coverages, was studied. Diffusion coefficients were calculated between 40 and 150K. The surface diffusion of adatoms appeared as a thermally activated process with activation energy of 2.99kJ/mol. The mechanism responsible for surface diffusion of the adsorbed atoms was investigated by comparing the simulation results with Chudley-Elliot and random-walk models. Analysis of the particle trajectories showed that the diffusive paths of the adatoms could be described as a non-Markovian chain, due to jump correlations induced by adatom-adatom interactions. An extension of the Chudley-Elliot model permitted the determination of jump-distance distributions from the intermediate self-scattering function. A Lorentzian distribution described very well the motion of Xe atoms in terms of jump diffusion.

Molecular Dynamics Simulation of Xe Diffusion on the Si(100)-2x1 Surface. Utrera, L., Ramírez, R.: The Journal of Chemical Physics, 1992, 96[10], 7838-47