EVOLUTION OF EQUILIBRIUM FORMS OF A 2-DIMENSIONAL KOSSEL CRYSTAL IN AVAPOR DIFFUSION FIELD - A MONTE-CARLO SIMULATION

We introduce a Monte Carlo model for the evolution of equilibrium inte rface morphologies from initially fully faceted (straight) forms. The two-dimensional model integrates the stochastic occupation of surface sites and the diffusive exchange of particles with the surrounding vap or phase, other surface sites and the underlying bulk solid. Neither l attice gas nor solid-on-solid (SOS) restrictions are imposed. The exch ange processes are associated with energy barriers, the absence of whi ch is shown to result, in particular at low temperatures, in physicall y unrealistic transition probabilities. For medium-sized model crystal s, the averaged shapes obtained through time averaging over a large nu mber of instantaneous configurations agree well with equilibrium shape s resulting from analytical models. The interface widths are considera bly larger than those resulting from SOS models, without significant i ncrease in the surface roughness. Crystal-size-dependent collective mo tions of solid particles in the interfacial region are observed. On la rger crystals the surface shape fluctuations have the character of cap illary waves. These results provide a new link between the macroscopic , thermodynamic shape of the interface and the microscopic origin of i nterface roughness.