LATTICE EFFECTS IN CRYSTAL EVAPORATION

We study the dynamics of a stepped crystal surface during evaporation, using the classical model of Burton, Cabrera and Frank, in which the dynamics of the surface is represented as a motion of parallel, monato mic steps. The validity of the continuum approximation treated by Fran k is checked against numerical calculations and simple, qualitative ar guments. The continuum approximation is found to suffer from limitatio ns related, in particular, to the existence of angular points. These l imitations are often related to the adatom detachment rate which is hi gher on the lower side of each step than on the upper side ('Schwoebel effect').