Equations of state and phase coexistence properties for simulated water

There is a practical need in modeling both ambient and high-temperature water near and above the critical point with a single transferable intermolecular potential. Thermodynamic properties for two water potentials, the simple point charge (SPC/E) and the polarizable point charge (PPC) models, are examined with the aid of molecular dynamics simulations. Analytical equations of state, liquid–vapor coexistence properties and critical point parameters are given. The effect of applying an external electric field to the system on the coexistence properties is investigated. A shift of the critical point of water to higher temperature and pressure is observed, a result similar to that of the introduction of an electrolyte to water.