Screening of Spherical Colloids beyond Mean Field -- A Local Density Functional Approach

TL;DR

This paper introduces a local density functional approach, the DHHC theory, to accurately model counterion distributions and osmotic pressure around spherical macroions, surpassing traditional Poisson-Boltzmann predictions.

Contribution

The paper develops and validates the DHHC theory, incorporating correlations into Poisson-Boltzmann theory, and demonstrates its improved accuracy over existing models.

Findings

DHHC theory agrees well with Monte Carlo simulations for weak correlations.

The zero temperature limit of DHHC captures trends for stronger correlations.

DHHC outperforms Poisson-Boltzmann theory in all tested cases.

Abstract

We study the counterion distribution around a spherical macroion and its osmotic pressure in the framework of the recently developed Debye-H"uckel-Hole-Cavity (DHHC) theory. This is a local density functional approach which incorporates correlations into Poisson-Boltzmann theory by adding a free energy correction based on the One Component Plasma. We compare the predictions for ion distribution and osmotic pressure obtained by the full theory and by its zero temperature limit with Monte Carlo simulations. They agree excellently for weakly developed correlations and give the correct trend for stronger ones. In all investigated cases the DHHC theory and its computationally simpler zero temperature limit yield better results than the Poisson-Boltzmann theory.