Atomistic Simulations of Acoustic Activation of Surface Processes

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This award supports computational research into the fundamental mechanisms of the energy transfer from strong acoustic waves to the atomic-scale surface features. Surface acoustic waves are elastic waves that propagate along the surfaces of solid materials. Their ability to transfer energy long distances with little losses are actively used in many practical applications, ranging from nondestructive evaluation of mechanical properties to micro-scale manipulation of fluid flow in microfluidics devices. The ability of surface acoustic waves to influence atomic-level surfaces processes, however, remains largely unexplored. The results of this research will facilitate the development of new applications in the areas of chemical catalysis, low temperature thin film growth, and mass spectrometry of heat sensitive molecules. At a more general level, the results of this study may open up an exciting range of opportunities for using the acoustic waves as an alternative source of energy for non-thermal activation of surface processes under conditions where the temperature increase must be avoided. The involvement of students into all aspects of high-performance parallel computing and close interaction with experimental and computational collaborators will create a fertile educational environment in the quickly expanding area of scientific computing.The goal of revealing the mechanisms responsible for the acoustic activation of surface processes will be achieved through the development of advanced computational methodology for atomistic modeling of free nonlinear propagation and dissipation of strong surface and bulk acoustic waves, as well as their interaction with surface structures and adsorbates. The new computational methods will be applied for a systematic investigation of frequency up-conversion, nonlinear sharpening of the wave profiles, shock formation and the onset of rapid dissipation of acoustic waves, acoustic energy coupling to surfaces adsorbates, sub-surface crystal defects, and nanoscale heterogeneities. The conditions leading to the diffusion enhancement, desorption, or atomic-level structural rearrangements in the surface region of the substrate will be elucidated in the simulations and the domains of applicability of the acoustically-assisted surface processing will be established for several material systems of practical interest.