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(305) Production(s) de KOB W.
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Accessing the Kauzmann temperature using computer simulations in equilibirum
Auteur(s): Kob W.
(Séminaires)
University La Sapienza (Rome, IT), 2012-06-21 |
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Finite size effects in the dynamics of glass-forming liquids 
Auteur(s): Berthier L., Biroli Giulio, Coslovich D., Kob W., Toninelli Cristina
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 86 p.031502 (2012)
Texte intégral en Openaccess : 
Ref HAL: hal-00705279_v1
Ref Arxiv: 1203.3392
DOI: 10.1103/PhysRevE.86.031502
WoS: 000308530600006
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
68 Citations
Résumé: We present a comprehensive theoretical study of finite size effects in the relaxation dynamics of glass-forming liquids. Our analysis is motivated by recent theoretical progress regarding the understanding of relevant correlation length scales in liquids approaching the glass transition. We obtain predictions both from general theoretical arguments and from a variety of specific perspectives: mode-coupling theory, kinetically constrained and defect models, and random first order transition theory. In the latter approach, we predict in particular a non-monotonic evolution of finite size effects across the mode-coupling crossover due to the competition between mode-coupling and activated relaxation. We study the role of competing relaxation mechanisms in giving rise to non-monotonic finite size effects by devising a kinetically constrained model where the proximity to the mode-coupling singularity can be continuously tuned by changing the lattice topology. We use our theoretical findings to interpret the results of extensive molecular dynamics studies of four model liquids with distinct structures and kinetic fragilities. While the less fragile model only displays modest finite size effects, we find a more significant size dependence evolving with temperature for more fragile models, such as Lennard-Jones particles and soft spheres. Finally, for a binary mixture of harmonic spheres we observe the predicted non-monotonic temperature evolution of finite size effects near the fitted mode-coupling singularity, suggesting that the crossover from mode-coupling to activated dynamics is more pronounced for this model. Finally, we discuss the close connection between our results and the recent report of a non-monotonic temperature evolution of a dynamic length scale near the mode-coupling crossover in harmonic spheres.
Commentaires: 19 pages, 10 figures
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Static and dynamic length scales in glass-forming systems
Auteur(s): Kob W.
(Séminaires)
NIST (Washington, US), 2012-06-08 |
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Static and dynamic length scales in glass-forming systems
Auteur(s): Kob W.
(Séminaires)
Oak Ridge National Laboratory (Knoxville, US), 2012-06-05 |
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Static and dynamic properties of sodium borosilicate liquids and glasses: insight from ab initio simulations
Auteur(s): Ispas S., Pedesseau L., Kob W.
Conference: International Conference on Advanced Materials Modelling (ICAMM) (Nantes, FR, 2012-06-13)
Résumé: We present a study of structural and dynamical properties of a liquid and glassy sodium borosilicate of composition 3Na2O-B2O3-6SiO2, study carried out using first principles molecular dynamics simulations. This glass composition is thus similar to the glass wool that is used in our daily life. The simulations were carried out within the DFT framework as implemented in the VASP code. The samples contained 320 atoms, which is rather demanding for ab initio calculations, but it has allowed to study the intermediate order in glasses. In particular, we have investigated how boron atoms integrate and modify the silica network.
Furthermore we have determined the vibrational properties and identified the contributions of the different species to the density of states. We found that 3- and 4-fold coordinated boron atoms give rise to specific features in the density of states. The infrared spectra of our glassy models is also presented and directly compared to experimental data.
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Structural, dynamic and electronic properties of sodium-silicate
glasses and liquids from ab initio simulations
Auteur(s): Kob W.
Conférence invité: Annual Meeting of the Glass and Optical Materials Division (St. Louis, US, 2012-05-20)
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Static point-to-set correlations in glass-forming liquids
Auteur(s): Berthier L., Kob W.
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 85 p.011102 (2012)
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