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Different glassy characteristics are related to either caging or dynamical heterogeneity

Pareek, P and Adhikari, M and Dasgupta, C and Nandi, SK (2023) Different glassy characteristics are related to either caging or dynamical heterogeneity. In: Journal of Chemical Physics, 159 (17).

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Official URL: https://doi.org/10.1063/5.0166404


Despite the enormous theoretical and application interests, a fundamental understanding of the glassy dynamics remains elusive. The static properties of glassy and ordinary liquids are similar, but their dynamics are dramatically different. What leads to this difference is the central puzzle of the field. Even the primary defining glassy characteristics, their implications, and if they are related to a single mechanism remain unclear. This lack of clarity is a severe hindrance to theoretical progress. Here, we combine analytical arguments and simulations of various systems in different dimensions and address these questions. Our results suggest that the myriad of glassy features are manifestations of two distinct mechanisms. Particle caging controls the mean, and coexisting slow- and fast-moving regions govern the distribution of particle displacements. All the other glassy characteristics are manifestations of these two mechanisms; thus, the Fickian yet non-Gaussian nature of glassy liquids is not surprising. We discover a crossover, from stretched exponential to a power law, in the behavior of the overlap function. This crossover is prominent in simulation data and forms the basis of our analyses. Our results have crucial implications on how the glassy dynamics data are analyzed, challenge some recent suggestions on the mechanisms governing glassy dynamics, and impose strict constraints that a correct theory of glasses must have. © 2023 Author(s).

Item Type: Journal Article
Publication: Journal of Chemical Physics
Publisher: American Institute of Physics Inc.
Additional Information: The copyright for this article belongs to author.
Keywords: Dynamics, Distribution of particles; Dynamical heterogeneities; Glassy dynamics; Glassy liquids; Moving regions; Non-Gaussian; Ordinary liquids; Particle displacement; Single mechanisms; Static properties, Glass
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 28 Feb 2024 12:50
Last Modified: 28 Feb 2024 12:50
URI: https://eprints.iisc.ac.in/id/eprint/83659

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