Strong pressure-energy correlations in van der Waals liquids

TL;DR

This paper demonstrates strong pressure-energy correlations in van der Waals liquids like Lennard-Jones, highlighting their relation to inverse power-law potentials and implications for liquid dynamics.

Contribution

It reveals the presence of strong pressure-energy correlations in simple van der Waals liquids and connects these to effective inverse power-law repulsive potentials.

Findings

Strong correlations in Lennard-Jones liquids

Correlations also in crystal and glass phases

Approximate 96% correlation in supercritical Argon

Abstract

Strong correlations between equilibrium fluctuations of the configurational parts of pressure and energy are found in the Lennard-Jones liquid and other simple liquids, but not in hydrogen-bonding liquids like methanol and water. The correlations, that are present also in the crystal and glass phases, reflect an effective inverse power-law repulsive potential dominating fluctuations, even at zero and slightly negative pressure. In experimental data for supercritical Argon, the correlations are found to be approximately 96%. Consequences for viscous liquid dynamics are discussed.