Gas-liquid coexistence for the bosons square-well fluid and the $\mbox{}^4$He binodal anomaly

TL;DR

This paper investigates the gas-liquid coexistence in a boson square-well fluid using a novel quantum Monte Carlo method, revealing how quantum effects influence critical points and observing binodal anomalies in helium-4.

Contribution

The study introduces a new quantum Gibbs ensemble Monte Carlo algorithm to analyze boson fluids and explores quantum effects on phase coexistence and anomalies.

Findings

Critical point shifts to lower temperatures with decreasing particle mass.

Quantum effects cause observable binodal anomalies in helium-4.

Method successfully recovers classical results in the infinite mass limit.

Abstract

The binodal of a boson square-well fluid is determined as a function of the particle mass through the newly devised quantum Gibbs ensemble Monte Carlo algorithm [R. Fantoni and S. Moroni, {\sl to be published}]. In the infinite mass limit we recover the classical result. As the particle mass decreases the gas-liquid critical point moves at lower temperatures. We explicitely study the case of a quantum delocalization de Boer parameter close to the one of $\mbox{}^4$He. For comparison we also determine the gas-liquid coexistence curve of $\mbox{}^4$He for which we are able to observe the binodal anomaly below the $\lambda$-transition temperature.