Equation of state of charged colloidal suspensions and its dependence on the thermodynamic route

TL;DR

This study examines how the thermodynamic route affects the equation of state in charged colloidal suspensions, revealing significant sensitivities and discrepancies depending on the method used, despite accurate predictions of pair interactions by the model.

Contribution

It demonstrates the dependence of the colloidal suspension's equation of state on the thermodynamic route within the Renormalized Jellium Model, highlighting issues of self-consistency.

Findings

Equation of state varies significantly with thermodynamic route.

RJM accurately predicts pair potentials and correlation functions.

Discrepancies are due to neglected electrostatic correlations.

Abstract

The thermodynamic properties of highly charged colloidal suspensions in contact with a salt reservoir are investigated in the framework of the Renormalized Jellium Model (RJM). It is found that the equation of state is very sensitive to the particular thermodynamic route used to obtain it. Specifically, the osmotic pressure calculated within the RJM using the contact value theorem can be very different from the pressure calculated using the Kirkwood-Buff fluctuation relations. On the other hand, Monte Carlo (MC) simulations show that both the effective pair potentials and the correlation functions are accurately predicted by the RJM. It is suggested that the lack of self-consistency in the thermodynamics of the RJM is a result of neglected electrostatic correlations between the counterions and coions.