Molecular dynamics study of liquid water under high compression

Abstract

The technique of computer simulation by molecular dynamics has been used to investigate highly compressed water at mass density 1.346 g/cm3. The calculations involve 216 rigid molecules, subject to an additive interaction (the ``ST2 potential'') whose strong anisotropic character has been shown to describe the hydrogen bond phenomenon. In the light of previous calculations on the same model at ordinary pressures, substantial restructuring of the liquid in response to compression is obvious. No evidence arises to support description of the liquid in terms of crystal structures of ices VI and VII, the solid forms that might be expected to be relevant at the chosen density. The calculations indicate that the initial effect of pressure increase (at 1 atm) leads to increased fluidity, as is known to be the case for real water.