Finite-size Scaling Study of Shear Viscosity Anomaly at Liquid-Liquid Criticality

TL;DR

This study uses finite-size scaling analysis of molecular dynamics simulations to accurately quantify the shear viscosity anomaly near liquid-liquid criticality in a binary Lennard-Jones mixture, confirming theoretical predictions.

Contribution

It demonstrates the effectiveness of the Nosé-Hoover thermostat in studying critical shear viscosity and provides the first detailed finite-size scaling analysis of this property at liquid-liquid criticality.

Findings

Shear viscosity exhibits a measurable critical anomaly.

Nosé-Hoover thermostat effectively captures critical behavior.

Simulation results confirm theoretical predictions.

Abstract

We study equilibrium dynamics of a symmetrical binary Lennard-Jones fluid mixture near its consolute criticality. Molecular dynamics simulation results for shear viscosity, $\eta$, from microcanonical ensemble are compared with those from canonical ensemble with various thermostats. It is observed that Nos\'{e}-Hoover thermostat is a good candidate for this purpose and so, is adopted for the quantification of critical singularity of $\eta$, to avoid temperature fluctuation (or even drift) that is often encountered in microcanonical simulations. Via finite-size scaling analysis of our simulation data, thus obtained, we have been able to quantify even the weakest anomaly, of all transport properties, that shear viscosity exhibits and confirm the corresponding theoretical prediction.