A study was made, of the collective diffusion of adatoms on a stepped substrate, by using the Langmuir gas model. The model allowed for modified potential barriers and wells near to step edges, as well as for differing pre-factors for intrinsic jump rates at step edges. The diffusion tensor was calculated by using projection operator techniques. A detailed study was made of the dependence of macroscopic collective diffusion upon the microscopic parameters of the model. Collective effects which were due to a finite coverage were shown to be pivotal, even at low coverages, in determining the influence of steps upon measurable activation barriers and effective pre-factors.

Diffusion on a Stepped Substrate: Collective Diffusion in the Langmuir Gas Model J.Merikoski, S.C.Ying: Physical Review B, 1997, 56[4], 2166-74