Dynamics of a charged simple fluid with exponential memory and two relaxation times
The memory function formalism is applied to the study of charge fluctuations in a symmetric simple fluid. We assume the ions interact through the Rammanathan-Friedman potential. We calculate the distribution function using the hypernetted-chain approximation and use an exponential form, depending on two relaxation times, for the second-order memory function. Following this procedure, two algebraic equations for the relaxation times are obtained. These can be solved using the fourth- and sixth-order frequency momenta, yielding expressions for the relaxation times in terms of the characteristic parameters of the system. This approach allows the analysis of the dynamical structure factor and the dynamical behavior of the charge fluctuations. A comparison of these results with some recently reported in which the distribution function is calculated via mean spherical approximation theory, shows clearly the limitations of mean-field formalisms to describe the dynamics of charged fluids.
Flores-Mena
JE
Instituto de Fisica de la Universidad Autonoma de Puebla, Apartado Postal J-48, Puebla 72570, Puebla, Mexico.
Carrillo
JL