A study was made of H-induced lattice distortions by using molecular dynamics simulation techniques. A 2-exponential interatomic potential for H-Nb interaction was proposed on the basis of recent first-principles calculations for the H-Nb system. The quasi-elastic diffuse scattering cross-section was determined and was compared with neutron scattering data. The importance of H motion was clarified by comparing the results of dynamic simulations with static defect models. It was found that the usual method for introducing the thermal motion of atoms, via the Debye-Waller factor, provided a rather imprecise description of the q-dependence of the scattering cross-section. There was also some evidence that the actual time-scale for H motion affected the shape of the scattering function at 450K while, at 300K, this effect was of minor importance. Upon comparing these predictions with experimental results, agreement was found with respect to the q-dependence - but not with respect to the absolute intensities.

B.Von Sydow, G.Wahnström: Physical Review B, 1996, 53[6], 3171-6