COMPARISON OF A FIXED-CHARGE AND A POLARIZABLE WATER MODEL

Molecular dynamics simulations are used to examine two models for water. The first model is the fixed-charge model introduced by Stillinger and Rahman and the second model is the polarizable model developed by Dang. The site-site, intermolecular pair distribution functions and the hydrogen bond lifetimes are determined for three fluid states for which neutron-diffraction determined pair functions exist. The trends in the pair functions and the bond lifetimes with decreasing density and increasing temperature for both models are similar, with the fixed-charge model pair functions changing more slowly, and the bond lifetimes more rapidly than those for the polarizable model. For the temperatures and densities examined, the explicit inclusion of polarization in the interactions appears to have a relatively small effect on the pair functions.