Nanosecond-scale simulations of the behaviour of one-dimensional water molecule chains adsorbed in Li-ABW zeolite were performed at various temperatures, for both fully hydrated material (where water diffusion was not present) and for partially hydrated material (where diffusion occurred). The structure and the vibrational spectrum of fully hydrated Li-ABW were in agreement with both experimental data and Car-Parrinello molecular dynamics results. Classical molecular dynamics simulations were extended to a nanosecond time-scale in order to study the flip motion of water molecules around their bisectors, and the dehydration mechanism at high temperatures. Based upon the results of the simulations, it was suggested that the dehydration proceeded via stepwise single-file diffusion. The diffusive mechanism appeared to be single-file motion: the molecules never passed each other, even at temperatures up to 800K, nor could they switch between different channels. When the mean square displacements were evaluated with respect to the centre of mass of the molecules hosted by each channel, the expected dependence upon the square root of time appeared.

Molecular Dynamics Simulation of Anomalous Diffusion of One-Dimensional Water Molecule Chains in Li-ABW Zeolite. Demontis, P., Stara, G., Suffritti, G.B.: Microporous and Mesoporous Materials, 2005, 86[1-3], 166-75