Modeling hydrogen transport in large disordered systems

Abstract

The diffusion of hydrogen in disordered structures (i.e. polycrystalline materials) can be modeled in terms of a network of transitions between neighbored local energetic minima. These networks have been generated for the tungsten–hydrogen system based on results of classical molecular dynamics simulations. The sparsity of the resulting energy-landscape-based networks enables within the transition-state theory approximation an efficient computation of the transport properties of hydrogen in large systems. The results confirm that grain boundaries in polycrystalline tungsten can provide a fast and extended transport channel. Finally, the relation of transition network approach with kinetic Monte Carlo is exploited to simulate break-through curves in a simple two-dimensional lattice model system.