A pair potential that reproduces the shape of isochrones in molecular liquids

Abstract

Many liquids have curves (isomorphs) in their phase diagrams along which structure, dynamics, and some thermodynamic quantities are invariant in reduced units. A substantial part of their phase diagrams is thus effectively one dimensional. The shape of these isomorphs is described by a material-dependent function of density $h(\rho )$, which for real liquids is well approximated by a power law ${\rho }^{\gamma }$. However, in simulations, a power law is not adequate when density changes are large; typical models such as the Lennard-Jones liquid show that $\gamma (\rho )\equiv \mathrm{d}\ln h(\rho )/\mathrm{d}\ln \rho$ is a decreasing function of density. This paper presents results from computer simulations using a new pair potential that diverges at a nonzero distance and can be tuned to give a more realistic shape of $\gamma (\rho )$. Our results indicate that the finite size of molecules is an important factor to take into account when modeling liquids over a large density range.

5 pages, 4 figures

References in corpus (10)

• Supercooled Liquids for Pedestrians
• Pressure-energy correlations in liquids. I. Results from computer simulations
• Strong pressure-energy correlations in van der Waals liquids
• Pressure-energy correlations in liquids. II. Analysis and consequences
• RUMD: A general purpose molecular dynamics package optimized to utilize GPU hardware down to a few thousand particles
• Pressure-energy correlations and thermodynamic scaling in viscous Lennard-Jones liquids
• Explaining why simple liquids are quasi-universal
• Invariants in the Yukawa system's thermodynamic phase diagram
• Freezing and melting line invariants of the Lennard-Jones system
• Density Scaling and Decoupling in o-Terphenyl, Salol, and Dibutyphthalate

Cited by in corpus (1)

• Intermolecular distance and density scaling of dynamics in molecular liquids