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(307) Production(s) de BERTHIER L.


Lengthscales in amorphous materials
Auteur(s): Berthier L.
Conférence invité: Miniworkshop on glasses (, FR, 20110412)



Microscopic theory of the jamming transition of harmonic spheres
Auteur(s): Berthier L., Jacquin Hugo, Zamponi Francesco
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 84 p.051103 (2011)
Texte intégral en Openaccess :
Ref HAL: hal00643045_v1
Ref Arxiv: 1106.4663
DOI: 10.1103/PhysRevE.84.051103
WoS: 000296958700001
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62 Citations
Résumé: We develop a microscopic theory to analyze the phase behaviour and compute correlation functions of dense assemblies of soft repulsive particles both at finite temperature, as in colloidal materials, and at vanishing temperature, a situation relevant for granular materials and emulsions. We use a meanfield statistical mechanical approach which combines elements of liquid state theory to replica calculations to obtain quantitative predictions for the location of phase boundaries, macroscopic thermodynamic properties and microstructure of the system. We focus in particular on the derivation of scaling properties emerging in the vicinity of the jamming transition occurring at large density and zero temperature. The new predictions we obtain for pair correlation functions near contact are tested using computer simulations. Our work also clarifies the conceptual nature of the jamming transition, and its relation to the phenomenon of the glass transition observed in atomic liquids.
Commentaires: 31 pages, 18 figures; long version of arXiv:1011.5638 Journal: Phys. Rev. E 84, 051103 (2011)



Testing "microscopic" theories of glassforming liquids
Auteur(s): Berthier L., Tarjus Gilles
(Article) Publié:
European Physical Journal E, vol. 34 p.96 (2011)
Texte intégral en Openaccess :
Ref HAL: hal00640665_v1
Ref Arxiv: 1105.3291
DOI: 10.1140/epje/i2011110965
WoS: 000295695400012
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32 Citations
Résumé: We assess the validity of "microscopic" approaches of glassforming liquids based on the sole k nowledge of the static pair density correlations. To do so we apply them to a benchmark provided by two liquid models that share very similar static pair density correlation functions while disp laying distinct temperature evolutions of their relaxation times. We find that the approaches are unsuccessful in describing the difference in the dynamical behavior of the two models. Our study is not exhausti ve, and we have not tested the effect of adding corrections by including for instance threebody density correlations. Yet, our results appear strong enough to challenge the claim that the slowd own of relaxation in glassforming liquids, for which it is well established that the changes of the static structure factor with temperature are small, can be explained by "microscopic" appr oaches only requiring the static pair density correlations as nontrivial input.
Commentaires: 10 pages, 7 figs; Accepted to EPJE Special Issue on The Physics of Glasses. Arxiv version contains an addendum to the appendix which does not appear in published version Journal: Eur. Phys. J. E 34, 96 (2011)



Highly nonlinear dynamics in a slowly sedimenting colloidal gel
Auteur(s): Cipelletti L., Brambilla G., Buzzaccaro Stefano, Piazza Roberto, Berthier L.
Conference: 8th Liquid Matter Conference (Vienne, AT, 20110906)
Ref HAL: hal00610242_v1
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Résumé: We use a combination of original light scattering techniques and particles with unique optical properties to investigate the behavior of suspensions of attractive colloids under gravitational stress, following over time the concentration profile, the velocity profile, and the microscopic dynamics [1,2]. During the compression regime, the sedimentation velocity grows nearly linearly with height, implying that the gel settling may be fully described by a (timedependent) strain rate. We find that the microscopic dynamics exhibit remarkable scaling properties when time is normalized by strain rate, showing that the gel microscopic restructuring is dominated by its macroscopic deformation. [1] G. Brambilla et al., Phys. Rev. Lett. 106, 118302 (2011). [2] "Gels settle down", in Physics, Spotlighting exceptional research http://physics.aps.org/synopsisfor/10.1103/PhysRevLett.106.118302



Theoretical perspective on the glass transition and amorphous materials
Auteur(s): Berthier L., Biroli Giulio
(Article) Publié:
Reviews Of Modern Physics, vol. 83 p.587 (2011)
Texte intégral en Openaccess :
Ref HAL: hal00608672_v1
Ref Arxiv: 1011.2578
DOI: 10.1103/RevModPhys.83.587
WoS: 000291803000001
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1172 Citations
Résumé: We provide a theoretical perspective on the glass transition in molecular liquids at thermal equilibrium, on the spatially heterogeneous and aging dynamics of disordered materials, and on the rheology of soft glassy materials. We start with a broad introduction to the field and emphasize its connections with other subjects and its relevance. The important role played by computer simulations to study and understand the dynamics of systems close to the glass transition at the molecular level is spelled out. We review the recent progress on the subject of the spatially heterogeneous dynamics that characterizes structural relaxation in materials with slow dynamics. We then present the main theoretical approaches describing the glass transition in supercooled liquids, focusing on theories that have a microscopic, statistical mechanics basis. We describe both successes and failures, and critically assess the current status of each of these approaches. The physics of aging dynamics in disordered materials and the rheology of soft glassy materials are then discussed, and recent theoretical progress is described. For each section, we give an extensive overview of the most recent advances, but we also describe in some detail the important open problems that, we believe, will occupy a central place in this field in the coming years.
Commentaires: 68 pages; 21 figs; 481 references Journal: Rev. Mod. Phys. 83, 587 (2011)



The role of attractive forces in viscous liquids
Auteur(s): Berthier L., Tarjus Gilles
(Article) Publié:
The Journal Of Chemical Physics, vol. 134 p.214503 (2011)
Texte intégral en Openaccess :
Ref HAL: hal00600672_v1
Ref Arxiv: 1103.0432
DOI: 10.1063/1.3592709
WoS: 000291402700027
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73 Citations
Résumé: We present evidence from computer simulation that the slowdown of relaxation of a standard LennardJones glassforming liquid and that of its reduction to a model with truncated pair potentials without attractive tails is quantitatively and qualitatively different in the viscous regime. The pair structure of the two models is however very similar. This finding, which appears to contradict the common view that the physics of dense liquids is dominated by the steep repulsive forces between atoms, is characterized in detail, and its consequences are explored. Beyond the role of attractive forces themselves, a key aspect in explaining the differences in the dynamical behavior of the two models is the truncation of the interaction potentials beyond a cutoff at typical interatomic distance. This leads us to question the ability of the jamming scenario to describe the physics of glassforming liquids and polymers.
Commentaires: 13 pages, 12 figures Journal: J. Chem. Phys. 134, 214503 (2011)



A microscopic meanfield theory of the jamming transition
Auteur(s): Jacquin Hugo, Berthier L., Zamponi Francesco
(Article) Publié:
Physical Review Letters, vol. 106 p.135702 (2011)
Texte intégral en Openaccess :
Ref HAL: hal00597233_v1
Ref Arxiv: 1011.5638
DOI: 10.1103/PhysRevLett.106.135702
WoS: 000289000100010
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49 Citations
Résumé: Dense particle packings acquire rigidity through a nonequilibrium jamming transition commonly observed in materials from emulsions to sandpiles. We describe athermal packings and their observed geometric phase transitions using fully equilibrium statistical mechanics and develop a microscopic manybody meanfield theory of the jamming transition for soft repulsive spherical particles. We derive analytically some of the scaling laws and exponents characterizing the transition and obtain predictions for microscopic correlation functions of jammed states that are amenable to experimental verifications, and whose accuracy we confirm using computer simulations.
Commentaires: 4 pages, 4 figs Journal: Phys. Rev. Lett. 106, 135702 (2011)
