Liquid-vapour asymmetry in pure fluids: A Monte Carlo simulation study

TL;DR

This study uses Monte Carlo simulations and finite-size-scaling theory to analyze liquid-vapour asymmetry in pure fluids, accurately determining critical parameters and universal distribution spectra.

Contribution

It introduces a field mixing transformation approach to map joint density-energy distributions onto critical scaling operators, enhancing critical point analysis.

Findings

Accurate critical point parameters obtained

Universal finite-size spectrum of distributions determined

Field mixing influences density distribution asymmetry

Abstract

Monte Carlo simulations within the grand canonical ensemble are used to obtain the joint distribution of density and energy fluctuations $p_L(\rho,u)$ for two model fluids: a decorated lattice gas and a polymer system. In the near critical region the form of $p_L(\rho,u)$ is analysed using a mixed field finite-size-scaling theory that takes account of liquid-vapour asymmetry. Field mixing transformations are performed that map $p_L(\rho,u)$ onto the joint distribution of critical scaling operators \ptMEstar\ appropriate to the Ising fixed point. Carrying out this procedure permits a very accurate determination of the critical point parameters. By forming various projections of \ptMEstar , the full universal finite-size spectrum of the critical density and energy distributions of fluids is also obtained. In the sub-critical coexistence region, an examination is made of the influence of field mixing on the asymmetry of the density distribution.