Ab initio calculation of the structure of molecular water in quartz

Abstract

Local-density-functional theory is used to determine the structure of molecular water along the c channel in α-quartz. We use a 105-atom cluster terminated by H atoms and find that water has a large effect on the silicate lattice. In particular it flips a Si─O─Si unit, which normally points inwards towards the centre of the c channel, outwards with the 0 atom of water exposed to the two Si atoms. The water molecule is bound with polarization forces between it and the deformed network.