Short-range structural transformations in water at high pressures

We report results of molecular dynamics simulations of liquid water at the temperature T = 277 K for a range of high pressure. One aim of the study was to test the model Amoeba potential for the description of equilibrium structural properties and dynamical processes in liquid water. In comparing our numerical results with the Amoeba and TIP5P potentials, our results of ab initio molecular dynamics simulations and the experimental data reveal that the Amoeba potential reproduces correctly structural properties of the liquid water. Another aim of our work was related with the investigation of the pressure induced structural transformations and their influence on the microscopic collective dynamics. We have found that the structural anomaly at the pressure pc ≈ 2000 Atm is related with the changes of the local, short-range order in liquid water within the first two coordination shells. This anomaly specifies mainly by deformation of the hydrogen-bond network. We also discuss in detail the anomalous behavior of sound propagation in liquid water at high pressures and compare numerical results with the experimental data.