Water molecules in single file: First-principles studies of one-dimensional water chains in zeolites

The static and dynamical properties of one-dimensional water chains confine d in zeolitic channels are studied by means of the Car Parrinello method. T he properties of such an unusual water structure, present in zeolites Li-AB W and bikitaite, are reported and compared. Differences in the zeolitic fra meworks are responsible for the different properties of the water chains. A more rigid chain structure is found in bikitaite, whereas our calculations predict that in Li-ABW water molecules are allowed some rotational degrees of freedom. We interpret such a finding on the basis of the different stre ngths of host-guest, dipolar interactions. Weaker interactions in Li-ABW al low for rotation of water molecules.