Charge Oscillations in Debye-Hueckel Theory

TL;DR

This paper applies the generalized Debye-Hueckel theory to ionic systems, deriving a charge-charge correlation function that satisfies key physical conditions and exhibits charge oscillations above a certain density threshold.

Contribution

It provides a complete and consistent expression for ionic charge correlations within the GDH framework, correcting previous assumptions and capturing charge oscillations.

Findings

Charge oscillations occur above the Kirkwood line in the (rho_N,T) plane.

The derived correlation function satisfies charge neutrality and Stillinger-Lovett conditions.

GDH theory offers a comprehensive description of ionic correlations, including near criticality.

Abstract

The recent generalized Debye-Hueckel (GDH) theory is applied to the calculation of the charge-charge correlation function G_{ZZ}(r). The resulting expression satisfies both (i) the charge neutrality condition and (ii) the Stillinger-Lovett second-moment condition for all T and rho_N, the overall ion density, and (iii) exhibits charge oscillations for densities above a "Kirkwood line" in the (rho_N,T) plane. This corrects the normally assumed DH correlations, and, when combined with the GDH analysis of the density correlations, leaves the GDH theory as the only complete description of ionic correlation functions, as judged by (i)-(iii), (iv) exact low-density (rho_N,T) variation, and (v) reasonable behavior near criticality.