Modeling diffusion in colloidal suspensions by dynamical density functional theory using fundamental measure theory of hard spheres

TL;DR

This paper develops a dynamical density functional theory approach using fundamental measure theory to model the diffusion dynamics of colloidal hard sphere suspensions, accurately matching simulation data up to high densities.

Contribution

It introduces a modified free energy functional within DDFT to accurately describe self-part interactions in colloidal suspensions.

Findings

The model accurately predicts van Hove functions up to 40% packing fraction.

The approach aligns well with dynamical Monte Carlo simulation data.

The method effectively captures the dynamics of dense colloidal suspensions.

Abstract

We study the dynamics of colloidal suspensions of hard spheres that are subject to Brownian motion in the overdamped limit. We obtain the time evolution of the self and distinct parts of the van Hove function by means of dynamical density functional theory (DDFT). The free energy model for the hard sphere fluid that we use is the very accurate White Bear II version of Rosenfeld's fundamental measure theory. However, in order to remove interactions within the self part of the van Hove function a non-trivial modification has to be applied to the free energy functional. We compare our theoretical results with data that we obtain from dynamical Monte Carlo simulations and find that the latter are well described by our approach even for colloid packing fractions as large as 40%.