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(327) Production(s) de BERTHIER L.
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Dynamic heterogeneity at the experimental glass transition predicted by transferable machine learning
Auteur(s): Jung G., Biroli Giulio, Berthier L.
(Article) Publié:
Physical Review B, vol. 109 p.064205 (2024)
Ref HAL: hal-04514863_v1
DOI: 10.1103/PhysRevB.109.064205
Exporter : BibTex | endNote
Résumé: We develop a machine learning model, which predicts structural relaxation from amorphous supercooled liquid structures. The trained networks are able to predict dynamic heterogeneity across a broad range of temperatures and time scales with excellent accuracy and transferability. We use the network transferability to predict dynamic heterogeneity down to the experimental glass transition temperature Tg, where structural relaxation cannot be analyzed using molecular dynamics simulations. The results indicate that the strength, the geometry, and the characteristic length scale of the dynamic heterogeneity evolve much more slowly near Tg compared to their evolution at higher temperatures. Our results show that machine learning techniques can provide physical insights on the nature of the glass transition that cannot be gained using conventional simulation techniques.
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Collective Relaxation Dynamics in a Three-Dimensional Lattice Glass Model
Auteur(s): Nishikawa Y., Berthier L.
(Article) Publié:
Physical Review Letters, vol. 132 p.067101 (2024)
Texte intégral en Openaccess :
Ref HAL: hal-04453684_v1
Ref Arxiv: 2307.08110
DOI: 10.1103/PhysRevLett.132.067101
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We numerically elucidate the microscopic mechanisms controlling the relaxation dynamics of a three-dimensional lattice glass model that has static properties compatible with the approach to a random first-order transition. At low temperatures, the relaxation is triggered by a small population of particles with low-energy barriers forming mobile clusters. These emerging quasiparticles act as facilitating defects responsible for the spatially heterogeneous dynamics of the system, whose characteristic lengthscales remain strongly coupled to thermodynamic fluctuations. We compare our findings both with existing theoretical models and atomistic simulations of glass-formers.
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Comment on “Fickian Non-Gaussian Diffusion in Glass-Forming Liquids”
Auteur(s): Berthier L., Flenner E., Szamel G.
(Article) Publié:
Physical Review Letters, vol. 131 p.119801 (2023)
Texte intégral en Openaccess :
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Front propagation in ultrastable glasses is dynamically heterogeneous
Auteur(s): Herrero C., Ediger Mark, Berthier L.
(Article) Publié:
The Journal Of Chemical Physics, vol. 159 p.114504 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04228257_v1
Ref Arxiv: 2304.12039
DOI: 10.1063/5.0168506
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Upon heating, ultrastable glassy films transform into liquids via a propagating equilibration front, resembling the heterogeneous melting of crystals. A microscopic understanding of this robust phenomenology is, however, lacking because experimental resolution is limited. We simulate the heterogeneous transformation kinetics of ultrastable configurations prepared using the swap Monte Carlo algorithm, thus allowing a direct comparison with experiments. We resolve the liquid–glass interface both in space and in time as well as the underlying particle motion responsible for its propagation. We perform a detailed statistical analysis of the interface geometry and kinetics over a broad range of temperatures. We show that the dynamic heterogeneity of the bulk liquid is passed on to the front that propagates heterogeneously in space and intermittently in time. This observation allows us to relate the averaged front velocity to the equilibrium diffusion coefficient of the liquid. We suggest that an experimental characterization of the interface geometry during the heterogeneous devitrification of ultrastable glassy films could provide direct experimental access to the long-sought characteristic length scale of dynamic heterogeneity in bulk supercooled liquids.
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Determination of pairwise interactions via the radial distribution function in equilibrium systems interacting with the Mie potential
Auteur(s): Tian Jianxiang, Berthier L.
(Article) Publié:
Results In Physics, vol. 52 p.106782 (2023)
Texte intégral en Openaccess :
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Two-Dimensional Crystals far from Equilibrium
Auteur(s): Galliano Leonardo, Cates Michael, Berthier L.
(Article) Publié:
Physical Review Letters, vol. 131 p.047101 (2023)
Ref HAL: hal-04184847_v1
DOI: 10.1103/PhysRevLett.131.047101
Exporter : BibTex | endNote
Résumé: When driven by nonequilibrium fluctuations, particle systems may display phase transitions and physical behaviour with no equilibrium counterpart. We study a two-dimensional particle model initially proposed to describe driven non-Brownian suspensions undergoing nonequilibrium absorbing phase transitions. We show that when the transition occurs at large density, the dynamics produces long-range crystalline order. In the ordered phase, long-range translational order is observed because equipartition of energy is lacking, phonons are suppressed, and density fluctuations are hyperuniform. Our study offers an explicit microscopic model where nonequilibrium violations of the Mermin-Wagner theorem stabilize crystalline order in two dimensions.
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Intermittent relaxation and avalanches in extremely persistent active matter
Auteur(s): Keta Y.-E., Mandal Rituparno, Sollich Peter, Jack Robert, Berthier L.
(Article) Publié:
Soft Matter, vol. 19 p.3871-3883 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04141015_v1
Ref Arxiv: 2212.09836
DOI: 10.1039/D3SM00034F
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We use numerical simulations to study the dynamics of dense assemblies of self-propelled particles in the limit of extremely large, but finite, persistence times. In this limit, the system evolves intermittently between mechanical equilibria where active forces balance interparticle interactions. We develop an efficient numerical strategy allowing us to resolve the statistical properties of elastic and plastic relaxation events caused by activity-driven fluctuations. The system relaxes via a succession of scale-free elastic events and broadly distributed plastic events that both depend on the system size. Correlations between plastic events lead to emergent dynamic facilitation and heterogeneous relaxation dynamics. Our results show that dynamical behaviour in extremely persistent active systems is qualitatively similar to that of sheared amorphous solids, yet with some important differences.
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