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arXiv · 2210.07119

Are supercooled liquids Fickian yet non Gaussian?

Ludovic Berthier·Elijah Flenner·Grzegorz Szamel
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Abstract

Comment on `Fickian Non-Gaussian Diffusion in Glass-Forming Liquids', by Rusciano et al., Phys. Rev. Lett. 128, 168001 (2022). In a recent Letter, Rusciano et al. examined the statistics of individual particles displacements in two-dimensional glass-formers and concluded that the corresponding probability distribution is non-Gaussian in a time regime where the mean-squared displacement is Fickian. Here, we clarify that the multiple length scales and time scales reported in this work have either been characterized before, or are not well-defined. This leads us to dispute the conclusions that glass-formers display Fickian non-Gaussian behaviour and that this analogy fruitfully addresses the central questions regarding the nature of dynamic heterogeneity in these systems.

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Ludovic Berthier, Elijah Flenner, Grzegorz Szamel. 2022-10-13. Are supercooled liquids Fickian yet non Gaussian?. https://doi.org/10.1103/physrevlett.131.119801

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