Annealing glasses by cyclic shear deformation

Abstract

A major challenge in simulating glassy systems is the ability to generate configurations that may be found in equilibrium at sufficiently low temperatures, in order to probe static and dynamic behaviour close to the glass transition. A variety of approaches have recently explored ways of surmounting this obstacle. Here, we explore the possibility of employing mechanical agitation, in the form of cyclic shear deformation, to generate low energy configurations in a model glass former. We perform shear deformation simulations over a range of temperatures, shear rates and strain amplitudes. We find that shear deformation induces faster relaxation towards low energy configurations, or overaging, in simulations at sufficiently low temperatures, consistently with previous results for athermal shear. However, for temperatures at which simulations can be run till a steady state is reached with or without shear deformation, we find that the inclusion of shear deformation does not result in any speed up of the relaxation towards low energy configurations. Although we find the configurations from shear simulations to have properties indistinguishable from an equilibrium ensemble, the cyclic shear procedure does not guarantee that we generate an equilibrium ensemble at a desired temperature. In order to ensure equilibrium sampling, we develop a hybrid Monte Carlo algorithm that employs cyclic shear as a trial generation step, and has acceptance probabilities that depend not only on the change in internal energy but also on heat dissipated (equivalently, work done). We show that such an algorithm indeed generates an equilibrium ensemble.

Extrapolation of high temperature relaxation times is not valid at lower temperatures because of a crossover in dynamics [see P. Das and S. Sastry, JNCS:X 14 (2022): 100098; arXiv:2204.04411], requiring a reinterpretation of the results. Additional results [Fig. 2 (c), Fig. A6] regarding overaging have been included. The material has been rearranged, with minor changes

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• A delayed yielding transition in mechanically annealed binary glasses at finite temperature
• Annealing effects of multidirectional oscillatory shear in model glass formers
• Relaxation dynamics in amorphous alloys under asymmetric cyclic shear deformation
• Structural relaxation and delayed yielding in cyclically sheared Cu-Zr metallic glasses
• Shear band healing in amorphous materials by small-amplitude oscillatory shear deformation
• Kinetic reconstruction of free energies as a function of multiple order parameters
• Inverse Bauschinger to Bauschinger Crossover under Steady Shear in Amorphous Solids