Dielectric relaxation of supercritical water: computer simulations

Abstract

The dielectric relaxation times of supercritical water SCW using the SPC/E model show strong deviations from the experimental measurements of K. Okada et al. (1997) in the low-density regime. The experimental dielectric relaxation time (DRT) exhibits a sharp rise as ρ decreases below 0.4 g/cm3, whereas a monotonic dependence of DRT with ρ is found in the simulations. Considering the overall highly nonexponential characteristics of the simulated normalized collective-dipole time correlation functions at low densities, the authors are led to believe that estimates for DRT obtained experimental by fitting the spectrum (up to 40 GHz) to a single Debye relation are likely to be highly uncertain.