(472f) Using First-Principles Calculations and Cluster Expansions to Model Hydrogen Diffusion in Metal Alloys

Diffusion of hydrogen in metals is important in numerous current and future applications of hydrogen, including hydrogen purification and storage. While plane wave Density Functional Theory calculations are well suited to giving local site-to-site information on diffusion paths and rates, this information is insufficient to describe net diffusive transport in disordered alloys. We will discuss how first-principles calculations, cluster expansion methods, and Kinetic Monte Carlo simulations can be combined to rigorously describe the net diffusion of interstitial in disordered alloys. Success in this task requires efficient use of first-principles methods, since hundreds or thousands of individual site energies and hopping rates are needed. We will discuss methods that allow us to rapidly locate hundreds of distinct transition states for diffusion of interstitial H in metals.