Ginzburg Criterion for Coulombic Criticality

TL;DR

This paper applies generalized Debye-Hueckel theories to the restricted primitive model of electrolytes, deriving a Landau-Ginzburg functional and evaluating the Ginzburg criterion to understand the crossover from classical to Ising critical behavior.

Contribution

It introduces a method to explicitly evaluate the Ginzburg criterion for Coulombic criticality using a Landau-Ginzburg functional derived from electrolyte models.

Findings

The crossover scale from classical to Ising behavior is similar to that in simple fluids.

The approach provides insights into experimental observations of electrolyte criticality.

The Landau-Ginzburg functional captures density correlations relevant to electrolyte phase transitions.

Abstract

To understand the range of close-to-classical critical behavior seen in various electrolytes, generalized Debye-Hueckel theories (that yield density correlation functions) are applied to the restricted primitive model of equisized hard spheres. The results yield a Landau-Ginzburg free-energy functional for which the Ginzburg criterion can be explicitly evaluated. The predicted scale of crossover from classical to Ising character is found to be similar in magnitude to that derived for simple fluids in comparable fashion. The consequences in relation to experiments are discussed briefly.