It was noted that quantitative applications of existing models for H diffusion by activated hopping and quantum tunnelling required large-scale first-principles calculations that were not well-suited to metal alloys which contained many structurally distinct interstitial sites. A semi-classically corrected version of harmonic transition-state theory, in conjunction with plane wave density functional theory, was used to examine H diffusion in multiple C15 Laves phase AB2 compounds and in body-centred cubic CuPd. A comparison with experimental data showed that this theory correctly captured the characteristics of H diffusion in these materials, over a wide range of temperatures. The method was applicable to complex alloys.

Quantitative Assessment of Hydrogen Diffusion by Activated Hopping and Quantum Tunneling in Ordered Intermetallics. B.Bhatia, D.S.Sholl: Physical Review B, 2005, 72[22], 224302 (8pp)