title: Significance of self-trapping on hydrogen diffusion.
abstract: The diffusion rate of hydrogen in Nb was calculated using ab initio molecular dynamics simulations. At low temperatures the hydrogen is strongly trapped in a local strain field which is caused by the elastic response of the lattice. At elevated temperatures, the residence time (τ) of hydrogen in an interstitial site is not sufficient for fully developing the local strain field. This unbinding of the interstitial hydrogen and the strain field increases the hopping rate (1/τ) at elevated temperatures (>400  K). These results call for a revision of the conceptual framework of diffusion of hydrogen in transition metals at elevated temperatures.
authors.affiliation: Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Blomqvist
authors.forename: Gunnar K
authors.initials: GK
authors.lastname: Pálsson
authors.forename: C Moysés
authors.initials: CM
authors.lastname: Araújo
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja
authors.forename: Björgvin
authors.initials: B
authors.lastname: Hjörvarsson