Accurate and Efficient Atomic-Scale Simulation of Structural Evolution in Materials: Metal Thin-Film Growth

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9617122 Fichthorn This theoretical research will advance the current capabilities for long-time, atomic-scale, dynamical simulations of materials by developing a family of new dynamical methods, based on Smart Monte Carlo. These methods are applicable to systems whose evolution is governed by rare-event dynamics. The inherent advantages of these methods are their accuracy, which is comparable to molecular dynamics simulations, and computational efficiency, which allows for simulation of long time scales on the order of minutes to hours. The new and extended capabilities of Smart Monte Carlo could have applications in the design and processing of many different kinds of materials, in catalysis, and in separations, where atomic- scale kinetics dictate macroscopic structure and function. These methods will be used to probe the relationship between kinetics and morphology in metal thin film epitaxy. Specifically, we will study cluster diffusion and its role in submonolayer metal thin film epitaxy for three model systems: Rh/Rh(001), Rh/Rh(111), and Pt/Rh(111). Recent studies indicate that complicated, many-atom mechanisms may mediate cluster diffusion in these systems and lead to unexpectedly high mobilities for large clusters. These findings have ramifications for thin film morphology, as well as for the development of theories for cluster diffusion and island growth, since current theories do not account for multiple-atom diffusion mechnaisms and large cluster mobilities. %%% This research is comprised of both the development of new computational techniques and the application of these techniques to the study of the deposition and movement of metal atoms on metal surfaces. These simulations, and associated theory, will help us understand how material films grow and form particular structures. The results of this work will advance computational methods and provide an important design tool for understanding the growth of materials. ***