LONG-TIME-SCALE SIMULATIONS OF AL(100) CRYSTAL GROWTH

摘要

We have carried out simulations of Al(100) crystal growth using a combination of classical dynamics simulations and a new long time scale simulation method based on harmonic transition state theory. Atoms are deposited using classical dynamics over a time interval of a few picoseconds, but once the system has thermalized, the long time interval in between deposition events, a millisecond, is simulated using an extension of the kinetic Monte Carlo method. Here, relevant transitions in the system are found on the fly and the need for a predetermined event table and lattice approximation are eliminated. For a given state of the system, the dimer method is used to search for the saddle points on the potential energy rim surrounding the local energy minimum. The Al(100) surface is found to grow remarkably smoothly, even at temperatures as low as 30 K. As multilayer structures start to form, low barrier events involving concerted displacement of a number of atoms tend to smoothen the surface.