2-DIMENSIONAL BROWNIAN-MOTION OF ATOMS AND DIMERS ON SOLID-SURFACES

In the present paper, the two-dimensional Brownian motion of single ad atoms and dimers on a solid surface is examined on the basis of Langev in equations. In these equations, a relation previously derived by the authors for the friction force is employed. The interaction between t he atoms and the solid surface is modeled by a decoupled cosine potent ial. Compared to the one-dimensional case treated previously by the au thors, the diffusion has to account in this case for the rotation of t he dimer. It is demonstrated that the diffusion coefficient of the dim ers exhibits a periodic dependence upon the ratio between the dimer le ngth and the solid lattice parameter, hence that there are maxima in t he diffusion coefficient. This effect, resonant diffusion, which was p resent in the one-dimensional case, is now affected in a major way by the rotation of the dimer.