Hydrogen bond statistics and dynamics in water: Self-diffusion and dielectric relaxation

Abstract

Dynamical properties of water up to the supercooled region are analyzed by explicitly taking into account the dynamics of the hydrogen bonds. The H-bond dynamics is described by means of a stochastic variable η exploring different states according to the number of H bonds established by the tagged molecule with its neighbors. Application of the ‘‘reduced’’ model theory leads to a master equation for the long-time diffusional properties of water, depending only on meaningful physical quantities that are obtained either from experiments and computer simulations or on the ground of physical considerations. Dielectric relaxation and self-diffusion behaviors are successfully reproduced and also recent results from incoherent neutron scattering can be rationalized.