8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P7.58Thu 811:10-14:00Liquid-vapor equilibrium properties of a water modelwith nonlinear polarizationPeter Kiss 1 and Andras Baranyai 11 Eotvos Lorand University, Nandorfejervari street 13, 1117, Budapest, HungaryAn indispensable test of the transferability of water models is to calculate their liquid-vapor equilibriumproperties. These calculations have already been done for numerous water models, nonpolarizableand polarizable as well. The nonpolarizable models underestimate the equilibrium vaporpressures, while the polarizable models (except GCPM and TIP4P-QDP-LJ) have critical pointsbelow 600K. We developed a new polarizable model of water. The electrostatic interactions arehandled with only three Gaussian charges. The magnitude and the position of the charges arechoosen to reproduce the experimental dipole moment and provide the best possible approximationof the quadrupole moments. We use the charge-on-spring method to polarize the molecules.Numerous ab initio calculations suggest that the polarizability of water in condensed phases issmaller than in the gas phase. The application of polarization damping at high electric fields wasunavoidable to obtain correct dielectric constant. The role and the necessity of this damping arediscussed. The nonelectrostatic parameters of the model were fitted to the properties of liquidwater at ambient conditions and for hexagonal ice, considering the dimer properties as well. Theliquid-vapor coexistence curve was calculated with direct coexistence simulations in NVT ensemble,using Ewald method to handle long-range electrostatics. Although the model was not fitted tosupercritial conditions, the critical properties are superior to other polarizable models.58