Eur. Phys. J. B 58, 449-459 (2007)
https://doi.org/10.1140/epjb/e2007-00247-7

Crossover behavior in fluids with Coulomb interactions

¹ Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine
² Laboratoire de Physique Théorique CNRS UMR 8627, Bât. 210, Université de Paris-Sud 91405 Orsay Cedex, Cedex, France

Corresponding author: ^a oksana@icmp.lviv.ua

Received: 5 April 2007
Revised: 1 August 2007
Published online: 22 September 2007

Abstract

According to extensive experimental findings, the Ginzburg temperature t_G for ionic fluids differs substantially from that of nonionic fluids [W. Schröer, H. Weigärtner, Pure Appl. Chem. 76, 19 (2004)]. A theoretical investigation of this outcome is proposed here by a mean field analysis of the interplay of short and long range interactions on the value of t_G. We consider a quite general continuous charge-asymmetric model made of charged hard spheres with additional short-range interactions (without electrostatic interactions the model belongs to the same universality class as the 3D Ising model). The effective Landau-Ginzburg Hamiltonian of the full system near its gas-liquid critical point is derived from which the Ginzburg temperature is calculated as a function of the ionicity. The results obtained in this way for t_G are in good qualitative and sufficient quantitative agreement with available experimental data.