Liquid-vapour phase behaviour of a symmetrical binary fluid mixture

TL;DR

This study uses Monte Carlo simulations and mean field calculations to explore the complex liquid-vapour phase diagram of a symmetrical binary fluid mixture, revealing various critical phenomena as interaction parameters vary.

Contribution

It provides new insights into the phase behaviour of binary mixtures, identifying critical end points, triple points, and tricritical points through combined simulation and theoretical methods.

Findings

Identification of critical end point behaviour

Discovery of a triple point involving vapor and two liquids

Prediction of a metastable liquid-vapour binodal

Abstract

Using Monte-Carlo simulation and mean field calculations, we study the liquid-vapour phase diagram of a square well binary fluid mixture as a function of a parameter $\delta$ measuring the relative strength of interactions between particles of dissimilar and similar species. The results reveal a rich variety of liquid-vapour coexistence behaviour as $\delta$ is tuned. Specifically, we uncover critical end point behaviour, a triple point involving a vapour and two liquids of different density, and tricritical behaviour. For a certain range of $\delta$, the mean field calculations also predict a `hidden' (metastable) liquid-vapour binodal.