A valence force field was optimized in order to reproduce the phonon dispersion curves of crystalline GaAs and derived interaction energies of Ga adatoms on the (001) surface. Calculations of the diffusion constant of isolated Ga atoms on the GaAs surface were performed by means of molecular dynamics simulations. All of the bulk Ga and As atoms, and the adsorbed Ga atoms, were completely free to move and no normalization of the velocity was performed after the trajectory had begun. Averages were taken of the results of hundreds of such trajectories for each temperature. Surface diffusion constants were then obtained from the (001) in-plane components. It was found that the data could be described by:

D(cm2/s) = 2.41 x 10-5 exp[-0.0971(eV)/kT]

A.Palma, E.Semprini, A.Talamo, N.Tomassini: Journal of Crystal Growth, 1995, 150[1-4], 180-4