Impact of Friedel oscillations on vapor-liquid equilibria and supercritical properties in 2D and 3D

TL;DR

This study investigates how Friedel oscillations influence phase behavior and critical properties in 2D and 3D systems using advanced simulations, revealing dimensionality-dependent effects and linear relationships in 3D.

Contribution

It introduces a comprehensive analysis of Friedel oscillations' impact on thermodynamics across dimensions using a combined Lennard-Jones and Dzugutov potential with variable oscillation height.

Findings

In 3D, critical parameters depend linearly on the oscillation control parameter X.

In 3D, ideality lines are straight and span subcritical and supercritical regions.

In 2D, Friedel oscillations have minimal effect on critical properties, with constant critical density.

Abstract

We determine the impact of the Friedel oscillations on the phase behavior, critical properties and thermodynamic contours in films ($2D$) and bulk phases ($3D$). Using Expanded Wang-Landau simulations, we calculate the grand-canonical partition function and, in turn, the thermodynamic properties of systems modeled with a linear combination of the Lennard-Jones and Dzugutov potentials, weighted by a parameter $X$ ($0<X<1$). Varying $X$ allows us to control the height of the first Friedel oscillation and to provide a complete characterization of the effect of the metal-like character in the potential on the thermodynamic properties over a wide range of conditions. For $3D$ systems, we are able to show that the critical parameters exhibit a linear dependence on $X$ and that the loci for the thermodynamic state points, for which the system shows the same compressibility factor or enthalpy as an ideal gas, are two straight lines spanning the subcritical and supercritical regions of the phase diagram for all $X$ values. Reducing the dimensionality to $2D$ results in a loss of impact of the Friedel oscillation on the critical properties, as evidenced by the virtually constant critical density across the range of $X$ values. Furthermore, our results establish that the straightness of the two ideality lines is retained in $2D$ and is independent from the height of the first Friedel oscillation in the potential.