Calculation of the Dielectric Constant of Water to 1000°C and Very High Pressures

Measured data for the dielectric constant of water exist to 550°C and 5000 bar and to 400°C and 3000 bar (critical temperature: 374°C). The present calculations extend to 1000°C and a density of 1 g cm−3 (16000 bar). Results are given for densities between 0.1 and 1 g cm−3 and for temperatures to 1000°C. From 400 to 1000°C at densities of 0.1, 0.5 and 1.0 g cm−3 the dielectric constant varies from 2.04 to 1.50, from 10.45 to 4.69 and from 29.4 to 11.06 respectively. The calculation is based on a hard‐sphere with dipole moment molecular interaction model and an approximate equation of Patey et al. based on a linearized hypernetted chain procedure. The effective hard sphere diameter of 2.68 Å has been derived from fitting to existing PVT data to 1000°C by a suitable equation of state. The effective dipole moment of 2.33 D was obtained from fitting to existing experimental dielectric constant values to 550°C and high densities with the Patey equation. Analogous calculations of the dielectric constants of supercritical, dense HCl, NH3 and CH3F are presented.