Weighted-density approximation for general nonuniform fluid mixtures

TL;DR

This paper develops an improved weighted-density approximation functional for multicomponent nonuniform fluid mixtures, enabling accurate phase diagram calculations at interfaces, and demonstrates its effectiveness through binary hard-sphere fluid analysis.

Contribution

It introduces a corrected extension of the weighted-density approximation for multicomponent systems, addressing previous limitations in spatially varying compositions.

Findings

Accurately predicts the freezing phase diagram of binary hard-sphere fluids.

Outperforms previous Denton-Ashcroft extension in nonuniform systems.

Aligns well with simulation data for phase transition points.

Abstract

In order to construct a general density-functional theory for nonuniform fluid mixtures, we propose an extension to multicomponent systems of the weighted-density approximation (WDA) of Curtin and Ashcroft [Phys. Rev. A 32, 2909 (1985)]. This extension corrects a deficiency in a similar extension proposed earlier by Denton and Ashcroft [Phys. Rev. A 42, 7312 (1990)], in that that functional cannot be applied to the multi-component nonuniform fluid systems with spatially varying composition, such as solid-fluid interfaces. As a test of the accuracy of our new functional, we apply it to the calculation of the freezing phase diagram of a binary hard-sphere fluid, and compare the results to simulation and the Denton-Ashcroft extension.