Density scaling as a property of strongly correlating viscous liquids

TL;DR

This paper confirms that density scaling of relaxation times in viscous liquids is valid for strongly correlating liquids and shows that the scaling exponent can be predicted from equilibrium fluctuations through computer simulations.

Contribution

It provides computational evidence supporting the conjecture that density scaling applies to strongly correlating viscous liquids and introduces a method to predict the scaling exponent from fluctuations.

Findings

Density scaling holds for strongly correlating liquids.

The scaling exponent can be accurately predicted from equilibrium fluctuations.

Simulations of model liquids confirm the conjecture.

Abstract

We address a recent conjecture according to which the relaxation time $\tau$ of a viscous liquid obeys density scaling ($\tau=F(\rho^\gamma/T)$ where $\rho$ is density) if the liquid is ``strongly correlating,'' i.e., has almost 100% correlation between equilibrium virial and potential-energy fluctuations [Pedersen {\it et al.}, PRL {\bf 100}, 011201 (2008)]. Computer simulations of two model liquids - an asymmetric dumbbell model and the Lewis-Wahnstr\"om OTP model - confirm the conjecture and demonstrate that the scaling exponent $\gamma$ can be accurately predicted from equilibrium fluctuations.