New mean-field theories for the liquid–vapour transition of charged hard spheres

Abstract

The phase behavior of the primitive model of electrolytes is studied in the framework of various mean field approximations obtained recently by means of methods pertaining to statistical field theory (CAILLOL, J.-M., 2004, J. Stat. Phys., 115, 1461. The role of the regularization of the Coulomb potential at short distances is discussed in details and the link with more traditional approximations of the theory of liquids is discussed. The values computed for the critical temperatures, chemical potentials, and densities are compared with available Monte Carlo data and other theoretical predictions.

Phase equilibria of size- and charge-asymmetric primitive models of ionic fluids: the method of collective variables

“…Within the framework of Gaussian approximation of the grand partition function, the best estimation for critical temperature is achieved for optimized regularization [28] that leads to an optimized random phase approximation. However, this approximation does not work properly in higher orders of perturbation theory [27]. Here we use the Weeks-Chandler-Andersen (WCA) regularization scheme for φ C αβ (r) [29].…”

“…It is worth noting that regularization of the potential φ C αβ (r) inside the hard core is arbitrary to some extent. For example, different regularizations for the Coulomb potential were considered in [26,27]. Within the framework of Gaussian approximation of the grand partition function, the best estimation for critical temperature is achieved for optimized regularization [28] that leads to an optimized random phase approximation.…”

The collective variables representation of simple fluids from the point of view of statistical field theory

“…We will introduce some reasonable approximation in section (5.2) to tackle with this horrible expression. Quite remarkably it has been shown recently that for a symmetric mixture of charged hard spheres ln Ξ (2) has a much more simple expression which involves only the pair correlation functions of the HS fluid as a consequence of local charge neutrality [19,23].…”

“…Firstly, equations (6) and (8) are easily generalized to the case of mixtures [19,23] or molecular fluids. Secondly, when the pair interaction w is neither attractive nor repulsive, it is necessary to introduce two real scalar fields ϕ + and ϕ − if some rigor is aimed at [10].…”

Phase behavior of the lattice restricted primitive model with nearest neighbor exclusion

“…Recent theoretical and simulation studies of ionic systems have improved our understanding of their structure and thermodynamics 1,2,3,4,5,6,7,8 . One of the most successful and simplest ionic models is the restricted primitive model (RPM), in which the ions are viewed as equisized hard spheres carrying positive and negative charges of the same magnitude.…”