Triplet depletion forces from density functional optimization

Abstract

A novel density functional theory optimization technique, based on Rosenfeld's “fundamental measure ” theory for hard-core particles and the use of an adaptive real-space grid, is developed to investigate highly asymmetric binary mixtures of hard spheres as models of bidisperse colloidal suspensions. The method is applied to the calculation of pair and triplet depletion forces between large colloids in a bath of much smaller colloidal particles. The computed pair forces are in generally good agreement with theoretical predictions and previous Monte Carlo work. The triplet forces, explicitly calculated for the first time, are an order of magnitude weaker than the much-studied pair interactions, and appear to be attractive.