Rapid local diffusion of hydrogen in niobium revealed by a molecular-dynamics study

Abstract
Molecular-dynamics simulations for hydrogen diffusion in Nb are performed at high temperatures (T=450 K and T=580 K). Two key experimental observations are reproduced by our model; the strong deviations from simple jump diffusion behavior and the ‘‘anomalous Debye-Walker’’ factor. The simulation reveals a rapid local-diffusion motion, predominantly confined to the so-called 4T configuration. The time scale for this motion is found to be of the order 100–200 fs.