Orientation relaxation of a water molecule

Abstract

A new interpretation of the low frequency (up to 1 THz) dielectric spectra of water based on the angular velocity autocorrelation function is proposed. We use Mori method to derive kinetic equations for the angular velovity autocorrelation function and obtain the angular velocity correlation time from the comaprison of the theoretical results with the inelastic neutron scattering experiment. using Hubbard relation we show that besides collection orientation relaxation, i.e. macroscopic dielectric relaxation, there is a single molecule orientation relaxation. It is much faster than the collective one and is displayed at the high frequency tail of the principle dielectric relaxation band. The analysis of the time dependence of the angular velovity autocorrelation function provides the evidence that the single-molecule relaxation is related to the molecules with partially broken II-bonds.