DENSITY-FLUCTUATIONS IN AN ELECTROLYTE FROM GENERALIZED DEBYE-HUCKEL THEORY

Near-critical thermodynamics in the hard-sphere (1,1) electrolyte is w ell described, at a classical level, by Debye-Huckel (DH) theory with (+,-) ion pairing and dipolar-pair-ionic-fluid coupling. But DH-based theories do not address density fluctuations. Here density correlation s are obtained by functional differentiation of DH theory generalized to nonuniform densities of various species. The correlation length xi diverges universally at low density rho as (T rho)(-1/4) (correcting t he generalized mean. spherical approximation). When rho = rho(c) one h as xi similar or equal to xi(0)(+)/t(1/2) as t = (T - T-c)/T-c --> 0+, where the amplitudes xi(0)(+) compare informatively with experimental data.