Mode-coupling theory of the stress-tensor autocorrelation function of a dense binary fluid mixture

TL;DR

This paper develops a generalized mode-coupling theory to analyze the stress-tensor autocorrelation function in dense binary fluid mixtures, revealing a significant long-time tail and the impact of compositional disorder.

Contribution

It introduces a new mode-coupling framework for dense binary mixtures, extending previous theories to account for compositional disorder effects.

Findings

STAF decays as t^{-3/2} over intermediate times

Long-time tail coefficient is over 100 times larger than in conventional theory

Compositional disorder significantly influences STAF decay

Abstract

We present a generalized mode-coupling theory for a dense binary fluid mixture. The theory is used to calculate molecular-scale renormalizations to the stress-tensor autocorrelation function (STAF) and to the long-wavelength zero-frequency shear viscosity. As in the case of a dense simple fluid, we find that the STAF appears to decay as $t^{-3/2}$ over an intermediate range of time. The coefficient of this long-time tail is more than two orders of magnitude larger than that obtained from conventional mode-coupling theory. Our study focuses on the effect of compositional disorder on the decay of the STAF in a dense mixture.