Continuous demixing at liquid-vapor coexistence in a symmetrical binary fluid mixture

TL;DR

This study uses Monte Carlo simulations to analyze the continuous demixing transition in a symmetrical Lennard-Jones binary fluid mixture at liquid-vapor coexistence, confirming Ising universality and contrasting with some theoretical predictions.

Contribution

It provides large-scale simulation evidence that the demixing transition is continuous and exhibits Ising universality, clarifying previous conflicting theoretical results.

Findings

Demixing transition is continuous at liquid-vapor coexistence.

The critical end point shows Ising-like universality.

Results confirm earlier simulation studies but contradict some theoretical approaches.

Abstract

We report a Monte Carlo finite-size scaling study of the demixing transition of a symmetrical Lennard-Jones binary fluid mixture. For equal concentration of species, and for a choice of the unlike-to-like interaction ratio delta=0.7, this transition is found to be continuous at liquid-vapor coexistence. The associated critical end point exhibits Ising-like universality. These findings confirm those of earlier smaller scale simulation studies of the same model, but contradict the findings of recent integral equation and hierarchical reference theory investigations.