Field theory for charged fluids and colloids

¹ Max-Planck-Institut für Kolloid- und Grenzflächenforschung Kantstr. 55, 14513 Teltow, Germany
² Service de Physique Théorique, CEA-Saclay, 91191 Gif sur Yvette, France

Received: 6 July 1998
Accepted: 6 January 1999

Abstract

Charged systems are considered using field theoretic methods which include fluctuations and correlations via a systematic expansion in powers of the local electrostatic potential. At the Gaussian level we recover the classical Debye-Hückel (DH) theory, which is found to exhibit the full hierarchy of multibody correlations determined by pair-distribution functions given by the screened DH potential. Higher-order corrections can lead to attractive pair interactions between similarly charged particles in asymmetric ionic environments. The phase diagram for an ionic fluid shows a critical point of demixing. The critical temperature and critical density exhibit pronounced deviations from DH theory for highly asymmetric ionic systems.