Supercritical water at ten densities from 0.1 gr/cc to 1.0 gr/cc at 1,000K using ab initio molecular dynamics simulations

Supercritical water is found inside Earth's Mantle, where water is subjected to very high temperatures and pressures. It exhibits extraordinary properties such as having a low dielectric constant and high reactivity, which stems from the breakdown of hydrogen bond network in supercritical state. This makes supercritical water a non-polar solvent and the basis for many innovative technologies. We investigate supercritical water at ten densities (0.1 gr/cc to 1.0 gr/cc) at 1,000K to study the structural correlations, such as atom resolved partial pair distributions, co-ordination numbers, bond-angle distributions and neutron scattering and x-ray structure factors. Among the dynamical correlations, we investigate the velocity autocorrelation function and current-current correlation function, and their Fourier transforms - vibrational density-of-states and frequency dependent dielectric constant. Structural and dynamical correlations are computed from time-trajectories of the positions and velocities calculated ab initio molecular dynamics within density functional theory (DFT) framework using the SCAN Exchange-Correlation functional. Our results for structural correlations are compared with the neutron scattering experiments on supercritical water by Soper and collaborators1 and dynamical correlations in supercritical state are compared with the inelastic neutron scattering results by Car and collaborators