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Transition vitreuse, hétérogénéité dynamique et vieillissement dans les systèmes a dynamique lente
(24) Production(s) de l'année 2023
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Computer simulations of the glass transition and glassy materials
Auteur(s): Barrat Jean-Louis, Berthier L.
(Article) Publié:
Comptes Rendus Physique, vol. 24 p.1-16 (2023)
Texte intégral en Openaccess :
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Liquid--Hexatic Transition for Soft Disks
Auteur(s): Nishikawa Y., Krauth Werner, Maggs A. C.
(Article) Publié:
Physical Review E, vol. 108 p.024103 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04076680_v1
Ref Arxiv: 2304.10143
DOI: 10.1103/PhysRevE.108.024103
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We study the liquid--hexatic transition of soft disks with massively parallel simulations and determine the equation of state as a function of system size. For systems with interactions decaying as the inverse $m$th power of the separation, the liquid--hexatic phase transition is continuous for $m = 12$ and $m=8$, while it is of first order for $m = 24$. The critical power $m$ for the transition between continuous and first-order behavior is larger than previously reported. The continuous transition for $ m=12 $ implies that the two-dimensional Lennard-Jones model has a continuous liquid--hexatic transition at high temperatures. We also study the Weeks--Chandler--Andersen model and find a continuous transition at high temperatures, that is consistent with the soft-disk case for $m=12$. Pressure data as well as our implementation are available from an open-source repository.
Commentaires: 7 pages, 4 figures
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Structure and elasticity of model disordered, polydisperse, and defect-free polymer networks
Auteur(s): Sorichetti V., Ninarello A. S., Ruiz-Franco José, Hugouvieux Virginie, Zaccarelli Emanuela, Micheletti Cristian, Kob W., Rovigatti Lorenzo
(Article) Publié:
The Journal Of Chemical Physics, vol. 158 p.074905 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04043309_v1
Ref Arxiv: 2211.04810
DOI: 10.1063/5.0134271
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: The elasticity of disordered and polydisperse polymer networks is a fundamental problem of soft matter physics that is still open. Here, we self-assemble polymer networks via simulations of a mixture of bivalent and tri- or tetravalent patchy particles, which result in an exponential strand length distribution analogous to that of experimental randomly cross-linked systems. After assembly, the network connectivity and topology are frozen and the resulting system is characterized. We find that the fractal structure of the network depends on the number density at which the assembly has been carried out, but that systems with the same mean valence and same assembly density have the same structural properties. Moreover, we compute the long-time limit of the mean-squared displacement, also known as the (squared) localization length, of the cross-links and of the middle monomers of the strands, showing that the dynamics of long strands is well described by the tube model. Finally, we find a relation connecting these two localization lengths at high density and connect the cross-link localization length to the shear modulus of the system.
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