Simulation of Crystal Growth with Surface Diffusion

Abstract

A computer simulation model is described which applies to the molecular processes involved in crystal growth under very general growth conditions. The transition probabilities used for adding and subtracting molecules from the crystal and for surface diffusion are shown to satisfy microscopic reversibility in equilibrium. The computer program uses several internal self‐consistency checks, the results of which support the validity of the simulation method. Growth measurements are obtained in a range above and below the surface roughening temperature. The growth rates of the (100) face of a Kossel crystal show a two‐dimensional nucleation barrier at low supersaturations and below the roughening temperature. An almost linear dependence on supersaturation is observed above this temperature. This result is independent of the amount of surface diffusion. A simple step model is described and the resulting growth rates are compared with the simulated rates of faces containing a fixed number of steps. Agreement is rather good at the lower temperatures and supersaturations. The same step model is used in conjunction with two‐dimensional nucleation theory to obtain growth rates for (100) faces, and the results are consistent with the simulated rates below the roughening temperature. A few simulations of dissolution (or evaporation) are included.