Structural-dynamical transition in the Wahnström mixture

Turci, Francesco; Speck, Thomas; Royall, C. Patrick

doi:10.1140/epje/i2018-11662-3

Cited by 18 publications

(21 citation statements)

References 70 publications

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“…Our results unambiguously demonstrate the existence of a discontinuous first-order phase transition in the ensemble of trajectories of polydisperse hard spheres between the normal liquid (low population of LFS and high mobility) and a non-equilibrium glassy phase (high population of LFS, the structural relaxation time exceeds the trajectory length). These results complement previous studies on two binary Lennard-Jones glass formers: Kob-Andersen [30,32,33,71] and Wahnström [71].…”

Section: Discussionsupporting

confidence: 91%

Dynamical coexistence in moderately polydisperse hard-sphere glasses

Campo

Speck

2020

The Journal of Chemical Physics

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We perform extensive numerical simulations of a paradigmatic model glass former, the hard-sphere fluid with 10% polydispersity. We sample from the ensemble of trajectories with fixed observation time, whereby single trajectories are generated by event-driven molecular dynamics. We show that these trajectories can be characterized in terms of local structure, and we find a dynamical-structural (active-inactive) phase transition between two dynamical phases: one dominated by liquid-like trajectories with low degree of local order and one dominated by glassy-like trajectories with a high degree of local order. We show that both phases coexist and are separated by a spatiotemporal interface. Sampling exceptionally long trajectories allows to perform a systematic finite-size scaling analysis. We find excellent agreement with Binder's scaling theory for first-order transitions. Interestingly, the coexistence region narrows at higher densities, supporting the idea of a critical point controlling the dynamic arrest. arXiv:1910.12045v1 [cond-mat.stat-mech]

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Section: Discussionsupporting

confidence: 91%

Dynamical coexistence in moderately polydisperse hard-sphere glasses

Campo

Speck

2020

The Journal of Chemical Physics

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“…Overall, our results are consistent with the idea that at least part of the dynamical slowdown is driven by the emergence of a set of locally favored structures, in agreement with earlier observations on these models (see, e.g., refs. 19 , 43 , 44 ). As the system is pushed closer to the glass transition, these structures become more stable, due to a more favorable local packing or potential energy, with a profound impact on both local and global dynamics 3 .…”

Section: Discussionmentioning

confidence: 99%

Autonomously revealing hidden local structures in supercooled liquids

et al. 2020

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Few questions in condensed matter science have proven as difficult to unravel as the interplay between structure and dynamics in supercooled liquids. To explore this link, much research has been devoted to pinpointing local structures and order parameters that correlate strongly with dynamics. Here we use an unsupervised machine learning algorithm to identify structural heterogeneities in three archetypical glass formers—without using any dynamical information. In each system, the unsupervised machine learning approach autonomously designs a purely structural order parameter within a single snapshot. Comparing the structural order parameter with the dynamics, we find strong correlations with the dynamical heterogeneities. Moreover, the structural characteristics linked to slow particles disappear further away from the glass transition. Our results demonstrate the power of machine learning techniques to detect structural patterns even in disordered systems, and provide a new way forward for unraveling the structural origins of the slow dynamics of glassy materials.

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“…Bottom: Population n * = Z * /(1 + Z * ) of excited states, which drops below the onset temperature To. We normalize Z * (To) = 1. arXiv:1902.07768v1 [cond-mat.stat-mech] 20 Feb 2019 finds support from simulations of atomistic model glass formers [15,16] and colloid experiments [17].…”

Section: Introductionmentioning

confidence: 91%

Dynamic facilitation theory: a statistical mechanics approach to dynamic arrest

Speck¹

2019

J. Stat. Mech.

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The modeling of supercooled liquids approaching dynamic arrest has a long tradition, which is documented through a plethora of competing theoretical approaches. Here, we review the modeling of supercooled liquids in terms of dynamic "defects", also called excitations or soft spots, that are able to sustain motion. To this end, we consider a minimal statistical mechanics description in terms of active regions with the order parameter related to their typical size. This is the basis for both Adam-Gibbs and dynamical facilitation theory, which differ in their relaxation mechanism as the liquid is cooled: collective motion of more and more particles vs. concerted hierarchical motion over larger and larger length scales. For the latter, dynamic arrest is possible without a growing static correlation length, and we sketch the derivation of a key result: the parabolic law for the structural relaxation time. We critically discuss claims in favor of a growing static length and argue that the resulting scenarios for pinning and dielectric relaxation are in fact compatible with dynamic facilitation.

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Structural-dynamical transition in the Wahnström mixture

Cited by 18 publications

References 70 publications

Dynamical coexistence in moderately polydisperse hard-sphere glasses

Dynamical coexistence in moderately polydisperse hard-sphere glasses

Autonomously revealing hidden local structures in supercooled liquids

Dynamic facilitation theory: a statistical mechanics approach to dynamic arrest

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