Universal non-Debye low-frequency vibrations in sheared amorphous solids

Abstract

We study energy minimized configurations of amorphous solids with a simple shear degree of freedom. We show that the low-frequency regime of the vibrational density of states of structural glass formers is crucially sensitive to the stress-ensemble from which the configurations are sampled. In both two and three dimensions, a shear-stabilized ensemble displays a $D({\omega }_{\min })\sim {\omega }_{\min }^5$ regime, as opposed to the ${\omega }_{\min }^4$ regime observed under unstrained conditions. We also study an ensemble of two dimensional, strained amorphous solids near a plastic event. We show that the minimum eigenvalue distribution at a strain $\gamma$ near the plastic event occurring at ${\gamma }_P$, displays a collapse when scaled by $\sqrt{{\gamma }_P-\gamma }$, and with the number of particles as $N^{-0.22}$. Notably, at low-frequencies, this scaled distribution displays a robust $D({\omega }_{\min })\sim {\omega }_{\min }^6$ power-law regime, which survives in the large $N$ limit. Finally, we probe the universal properties of this ensemble through a characterization of the second and third eigenvalues of the Hessian matrix near a plastic event.

6 pages, 4 figures, +Supplemental Material, changes: clarifications, 3D data, schematics

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• Predicting plasticity of amorphous solids from instantaneous normal modes
• Enhanced Vibrational Stability in Glass Droplets
• Universal Density of Low Frequency States in Silica Glass at Finite Temperatures
• Further testing the validity of generalized heterogeneous-elasticity theory for low-frequency excitations in structural glasses