Phase behaviour of a symmetrical binary fluid mixture in a field

TL;DR

This study investigates the phase behaviour of a symmetrical binary fluid mixture under an external field using integral equation theory and Monte Carlo simulations, revealing two distinct phase diagram subtypes and demonstrating good agreement between methods.

Contribution

It introduces a detailed analysis of phase diagrams of binary mixtures in fields, highlighting two subtypes and comparing theoretical and simulation results.

Findings

Identification of two phase behaviour subtypes in a binary mixture under a field.

Good agreement between MSA calculations and Monte Carlo simulations.

Detailed phase diagrams showing the influence of an external field.

Abstract

Integral equation theory calculations within the mean spherical approximation (MSA) and grand canonical Monte Carlo (MC) simulations are employed to study the phase behaviour of a symmetrical binary fluid mixture in the presence of a field arising from unequal chemical potentials of the two particle species. Attention is focused on the case for which, in the absence of a field, the phase diagram exhibits a first order liquid-liquid transition in addition to the liquid-vapor transition. We find that in the presence of a field, two possible subtypes of phase behaviour can occur, these being distinguished by the relationship between the critical lines in the full phase diagram of temperature, density, and concentration. We present the detailed form of the respective phase diagrams as calculated from MSA and compare with results from the MC simulations, finding good overall agreement.