The dynamics of hydrogen molecules, trapped in carbon nanotubes, were analyzed; with emphasis place on motion along the tube axis. In the configuration used, the hydrogen molecules disposed themselves in a cylindrical shell around the tube axis. Previous results, which suffered from finite size-effects, were corrected and the analysis was extended to the self-intermediate scattering function. It was found that the self-intermediate scattering function reached the free particle regime for wave vectors smaller than the one corresponding to the first diffraction maximum. This behavior was shown to stem from the quasi two-dimensional arrangement of hydrogen molecules inside the carbon nanotubes.

Space-Dependent Diffusion of Hydrogen in Carbon Nanotubes. G.Garberoglio, R.Vallauri: Journal of Molecular Liquids, 2005, 117[1-3], 43-7