The theoretical study of dielectric properties of water using the modified Onsager-Kirkwood-Fr?hlich theory

摘要

In the work, we present the new method for calculation dielectric properties for Water in the wide temperature range. We use the modified Onsager-Kirkwood-Fr?hlich theory, which makes it possible to calculate the polarization characteristics without using the static permittivity. We assumed that the dielectric is an isotropic medium consisting of molecules that do not interact with each other and are located in molecular electric fields. It allows us to use the average cosine of the angle between local electric field vectors and the dipole moment vectors of molecules in a medium as the average measure of the local orientation of the dipoles. This approach also makes it possible to equate the value of the energy of the interaction of dipoles with molecular fields to the value of the internal interaction energy if the energy of the interaction of the dipoles with external fields used for the experimental determination of the value of static permittivity is much less than the energy of the interaction. The calculated values of the dipole moment agree with the modern quantum mechanical calculations, and the results of calculating the values of permittivity are in practical agreement with experiment in the wide range of123.15K-573.15K. The method allows to calculate the static permittivity of water in various aggregate states: ice Ih in the range from 123K to melting point, supercooled water in the range from 238K to melting point, water at the saturation line from the melting point to the precritical region.