Molecular Dynamics Simulation Study of Superhydrated Perdeuterated Natrolite

In order to test a new interaction potential, Molecular Dynamics simulations of zeolite natrolite were performed for the structures at ambient conditions hydrated by perdeuterated water and at high pressure (1.87 GPa) in the superhydrated phase, which were recently studied by neutron diffraction. The experimental structures were reproduced with a reasonable accuracy and the hydrogen bond features is discussed. Like in ordinary natrolite, a flip motion of water molecules around the HOH bisector is found, which, together with translational oscillations gives rise to transient hydrogen bonds between water molecules, which do not appear from experimental equilibrium co-ordinates.
The dynamics of water molecules can explain some problems encountered in refining the experimental structure. Vibrational spectra of natrolite containing perdeuterated water, which are not yet measured, were simulated and their qualitative trend is discussed.