Instantaneous Normal Modes Reveal Structural Signatures for the Herschel-Bulkley Rheology in Sheared Glasses

TL;DR

This study uses atomistic simulations to identify that imaginary modes in the vibrational spectrum of sheared glasses are key structural signatures underlying the Herschel-Bulkley rheology law.

Contribution

It reveals that negative eigenvalue modes in the vibrational spectrum are directly linked to the Herschel-Bulkley rheology in sheared glasses, providing a structural origin.

Findings

Imaginary modes correlate with shear stress behavior.

Structural signatures identified for Herschel-Bulkley law.

Simulation results support the link between vibrational modes and rheology.

Abstract

The Herschel-Bulkley law, a universal constitutive relation, has been empirically known to be applicable to a vast range of soft materials, including sheared glasses. Although the Herschel- Bulkley law has attracted public attention, its structural origin has remained an open question. In this letter, by means of atomistic simulation of binary Lennard-Jones glasses, we report that the instantaneous normal modes with negative eigenvalues, or so-called imaginary modes, serve as the structural signatures for the Herschel-Bulkley rheology in sheared glasses.