Vibrational modes identify soft spots in a sheared disordered packing

TL;DR

This study uses vibrational mode analysis in a sheared disordered solid to identify soft spots that predict where particle rearrangements occur, revealing insights into the flow mechanism of amorphous materials.

Contribution

It introduces a method to identify soft spots in disordered solids using vibrational modes, linking them to localized rearrangements and flow behavior.

Findings

Soft spots are structurally distinct regions in the material.

Soft spots evolve slowly compared to rearrangement intervals.

Rearrangements tend to occur at identified soft spots.

Abstract

We analyze low-frequency vibrational modes in a two-dimensional, zero-temperature, quasistatically sheared model glass to identify a population of structural "soft spots" where particle rearrangements are initiated. The population of spots evolves slowly compared to the interval between particle rearrangements and the soft spots are structurally different from the rest of the system. Our results suggest that disordered solids flow via localized rearrangements that tend to occur at soft spots, which are analogous to dislocations in crystalline solids.