Finite-size scaling and particle size cutoff effects in phase separating polydisperse fluids

TL;DR

This paper presents a finite-size scaling method to accurately determine phase transition points in polydisperse fluids using simulations, highlighting the impact of particle size cutoff on phase behavior.

Contribution

It introduces a novel finite-size scaling approach for phase boundary detection in polydisperse fluids and examines the influence of particle size cutoff on phase behavior.

Findings

Finite-size scaling enables accurate cloud point detection from a single system size.

Cloud point density is highly sensitive to large particle presence.

Particle size cutoff significantly affects phase behavior reproducibility.

Abstract

We study the liquid-vapor phase behaviour of a polydisperse fluid using grand canonical simulations and moment free energy calculations. The strongly nonlinear variation of the fractional volume of liquid across the coexistence region prevents naive extrapolation to detect the cloud point. We describe a finite-size scaling method which nevertheless permits accurate determination of cloud points and spinodals from simulations of a single system size. By varying a particle size cutoff we find that the cloud point density is highly sensitive to the presence of rare large particles; this could affect the reproducibility of experimentally measured phase behavior in colloids and polymers.