Rosenfeld functional for non-additive hard spheres

TL;DR

This paper extends the fundamental measure density functional theory to binary mixtures of non-additive hard spheres, accurately predicting phase separation and correlation functions across various non-additivities and size ratios.

Contribution

It introduces a generalized functional for non-additive hard spheres and validates its predictions against simulation data for phase behavior and correlations.

Findings

Accurate prediction of fluid-fluid phase separation

Good agreement of correlation functions with simulations

The theory works for a wide range of non-additivities and size ratios

Abstract

The fundamental measure density functional theory for hard spheres is generalized to binary mixtures of arbitrary positive and moderate negative non-additivity between unlike components. In bulk the theory predicts fluid-fluid phase separation into phases with different chemical compositions. The location of the accompanying critical point agrees well with previous results from simulations over a broad range of non-additivities and both for symmetric and highly asymmetric size ratios. Results for partial pair correlation functions show good agreement with simulation data.