Integral equation study of effective attraction between like-charged particles mediated by cations: Comparison between IPY2 and HNC closures

TL;DR

This study compares two integral equation theories, HNC and IPY2, in predicting effective attractions between like-charged particles in electrolytes, revealing differences in concentration dependence and validating results with Monte Carlo simulations.

Contribution

It provides a comparative analysis of HNC and IPY2 closures in modeling electrostatic interactions, highlighting the reentrant behavior captured by HNC but not by IPY2.

Findings

HNC-OZ predicts reentrant behavior in electrolyte concentration dependence.

IPY2-OZ does not show reentrant behavior.

Monte Carlo simulations qualitatively agree with HNC predictions.

Abstract

Effective interactions between like-charged particles immersed in an electrolyte solution were calculated using two integral equation theories, hypernetted-chain (HNC)-Ornstein--Zernike (OZ) and ionic Percus--Yevick 2 (IPY2)-OZ. When the HNC-OZ theory was adopted, the electrolyte concentration dependence of the effective interaction showed a reentrant behavior. By contrast, the IPY2-OZ theory did not indicate the behavior. Monte Carlo simulations were performed for one of the model systems, and the results agreed qualitatively with those calculated using the HNC-OZ theory.