PROPERTIES OF SUPERCRITICAL WATER - AN AB-INITIO SIMULATION

Using ab initio molecular dynamics we have simulated the properties of supercritical water at the density rho=0.64 g/cm3 and temperature T=730 K. We calculate the neutron diffraction structure factors for various isotopic concentrations and find excellent agreement with experiment. The real-space pair correlations are qualitatively similar and our calculations confirm that the conditions prevalent in supercritical water disrupt the hydrogen bond network which characterizes water at ambient temperatures and pressure. In a quantitative respect there are significant differences between the simulation results for the pair correlation functions and those obtained from the inversion of the experimental data. We also studied some electronic properties of the system such as the average molecular dipole moment.