Yielding of a model glass former: An interpretation with an effective system of icosahedra

R Pinney and TB Liverpool and CP Royall, PHYSICAL REVIEW E, 97, 032609 (2018).

DOI: 10.1103/PhysRevE.97.032609

We consider the yielding under simple shear of a binary Lennard-Jones glass former whose super-Arrhenius dynamics are correlated with the formation of icosahedral structures. We recast this glass former as an effective system of icosahedra Pinney et al., J. Chem. Phys. 143, 244507 (2015). Looking at the small-strain region of sheared simulations, we observe that shear rates affect the shear localization behavior particularly at temperatures below the glass transition as defined with a fit to the Vogel-Fulcher-Tamman equation. At higher temperature, shear localization starts immediately on shearing for all shear rates. At lower temperatures, faster shear rates can result in a delayed start in shear localization, which begins close to the yield stress. Building from a previous work which considered steady-state shear Pinney et al., J. Chem. Phys. 143, 244507 (2015), we interpret the response to shear and the shear localization in terms of a local effective temperature with our system of icosahedra. We find that the effective temperatures of the regions undergoing shear localization increase significantly with increasing strain (before reaching a steady- state plateau).

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