HYDROGEN-BONDING IN SUPERCRITICAL WATER - A MONTE-CARLO SIMULATION

A detailed analysis of hydrogen bonding in supercritical water is made from Monte Carlo simulations along the 773 K isotherm over a wide range of pressures from 10 to 10000 MPa. It is shown that an energetic definition of H-bonding is much more effective in separating K-bonded and non-bonded molecular pairs than the widely used geometric definition, whereas a combination of both may be yet preferable at high pressures. Compared to H bonds in liquid water, the H bonds at 773 K are, on average, 10% weaker, 5% longer, and more bent. The quantitative characteristics of supercritical H bonds remain almost invariant over the entire pressure range studied.