Note: Gas-liquid crossover in the Lennard-Jones system

TL;DR

This paper identifies a universal density ratio at which the gas-liquid crossover occurs in the Lennard-Jones system, leading to a simple expression for the crossover line that aligns with recent definitions.

Contribution

It introduces a fixed density ratio for the gas-liquid crossover in the Lennard-Jones system, simplifying the phase diagram analysis.

Findings

Crossover occurs at $ ho/ ho_{ m fr} imeq 0.35$

The crossover line can be expressed simply based on this ratio

The definition aligns with recent alternative approaches

Abstract

It is demonstrated that the crossover between gas- and liquid-like regions on the phase diagram of the Lennard-Jones system occurs at a fixed value of the density divided by its value at the freezing point, $\rho/\rho_{\rm fr}\simeq 0.35$. This definition is consistent with other definitions proposed recently. As a result a very simple practical expression for the gas-to-liquid crossover line emerges.