Studies of liquid water by computer simulations. V. Equation of state of fluid water with Carravetta–Clementi potential

The pressure of liquid water at normal density is obtained by molecular dynamics simulations based on four intermolecular potential functions derived from quantum chemical calculations of the water dimer; Matsuoka–Clementi–Yoshimine, Carravetta–Clementi, Clementi–Habitz, Yoon–Morokuma–Davidson. Among them, the Carravetta–Clementi potential gives the most reasonable temperature-dependence of pressure, although the absolute value is large compared with the experimental one. The fluid state is surveyed over a wide range of temperature and density with the Carravetta–Clementi potential. The equation of state of fluid water is determined by a least-square fitting of the calculated energies and pressures at 347 state points. The anomalous properties of liquid water observed experimentally are nonempirically reproduced on a semiquantitative level. The calculated equation of state of liquid water is consistent with the Speedy–Angell conjecture on the limit of stability of the liquid phase.