Critical Dynamics in a Binary Fluid: Simulations and Finite-size Scaling

TL;DR

This paper presents detailed simulations of a symmetric binary fluid near its critical point, confirming theoretical predictions for viscosity and diffusion behavior while resolving previous simulation controversies.

Contribution

It provides comprehensive simulation data that validate renormalization-group and mode-coupling theories for critical dynamics, addressing finite-size effects and background contributions.

Findings

Viscosity and mutual diffusion follow predicted power laws

Self-diffusion coefficient shows no critical anomaly

Finite-size effects are crucial for accurate results

Abstract

We report comprehensive simulations of the critical dynamics of a symmetric binary Lennard-Jones mixture near its consolute point. The self-diffusion coefficient exhibits no detectable anomaly. The data for the shear viscosity and the mutual-diffusion coefficient are fully consistent with the asymptotic power laws and amplitudes predicted by renormalization-group and mode-coupling theories {\it provided} finite-size effects and the background contribution to the relevant Onsager coefficient are suitably accounted for. This resolves a controversy raised by recent molecular simulations.