Hydrogen bonding and the static dielectric constant in liquid water

Abstract

The static dielectric constants of several models for water are compared. These models have in common that they all give a good description of the energetics and structure of the hydrogen bonding in the liquid. Despite this similarity, the average molecular dipole moments vary over a range of 50% and the dielectric constants can differ by as much as a factor of 6. This observation verifies that the average dipole moment is a crucial parameter for the dielectric properties. On the other hand, this quantity seems of less importance for the stability of the hydrogen bonded network, which is largely determined by the details of the electrostatic and atom–atom interactions at short range. Applying this analysis we construct a polarizable model for liquid water with an average dipole moment of 2.6 D and a dielectric constant of 85. The structure and self-diffusion coefficient are in good agreement with experiment, and the value of the dimer binding energy in the gas phase is also acceptable.