Correlation between plastic rearrangements and local structure in a cyclically driven glass.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Investigating local structure-rearrangement correlations is crucial for understanding glass behavior.
• Glass forming liquids and glasses exhibit complex structural dynamics under stress.

Purpose of the Study:

• To explore correlations between local structural order parameters and plastic rearrangements in a model glass under cyclic shear.
• To identify key structural indicators predicting particle mobility during deformation.

Main Methods:

• Utilized excess two-body entropy (S2) and tetrahedrality (ntet) as per-particle local order parameters.
• Subjected a 3D model glass to cyclic shear deformation, both athermally and at varying strain amplitudes.
• Analyzed inherent structures and liquid configurations at different temperatures.

Main Results:

• Local ordering increases with decreasing temperature, indicated by decreased S2 and increased ntet.
• Under cyclic shear, glasses reach absorbing states for small amplitudes and form shear bands at large amplitudes.
• Particles with higher S2 and lower ntet are more likely to undergo rearrangements, regardless of energy or strain.
• Distinct local order observed outside shear bands, with higher prevalence of icosahedral clusters.

Conclusions:

• Local structural parameters (S2, ntet) effectively predict plastic rearrangement propensity in sheared glasses.
• Shear banding dynamics are influenced by the surrounding local structural environment.
• The study provides insights into the microscopic mechanisms governing deformation and structural evolution in amorphous materials.