An analysis was made of the dynamics of H molecules trapped in nanotubes, with emphasis being placed upon motion along the tube axis. In the configuration used here, the H molecules disposed themselves in a cylindrical shell around the tube axis. Corrections were made to some previous results, which suffered from finite size-effects and extended the analysis 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 behaviour was shown to arise from the quasi 2-dimensional arrangement of the H molecules inside the nanotubes.

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