Smoluchowski fluctuation theory of dielectric relaxation

Abstract

A recently proposed theory for transport coefficients in ionic solutions can be reinterpreted so that it becomes applicable to calculating the dielectric relaxation processes in dipolar fluids and in ionic solutions in dipolar solvents. The resulting theory is the same as the Smoluchowski–Vlasov theory which has been derived in various other ways by Munakata, Calef and Wolynes, and Chandra and Bagchi. Here the theory is applied to calculate the time correlation function for the fluctuating polarization density field in simple dipolar fluid, and in an ionic solution in a dipolar solvent. The results are similar to those derived some time ago by Berne using a ‘‘forced diffusion equation’’ as the theory for calculating the response. Comparison is also made with the results of Chandra and Bagchi using the Smoluchowski–Vaslov theory.