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(317) Production(s) de KOB W.
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Computer Simulations of Glassy Systems
Auteur(s): Kob W.
Conférence invité: School on Computer SImulations (Wildbad Kreuth, DE, 2013-09-16)
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Gelling by Heating 
Auteur(s): Roldan-Vargas Sandalo, Smallenburg Frank, Kob W., Sciortino Francesco
(Article) Publié:
Scientific Reports, vol. 3 p.2451 (2013)
Texte intégral en Openaccess : 
Ref HAL: hal-00858675_v1
DOI: 10.1038/srep02451
WoS: 000323147500001
Exporter : BibTex | endNote
25 Citations
Résumé: We exploit the concept of competing interactions to design a binary mixture of patchy particles that forms a reversible gel upon heating. Our molecular dynamics computer simulation of such a system shows that with increasing temperature the relaxation dynamics slows down by more than four orders of magnitude and then speeds up again. The system is thus a fluid both at high and at low temperatures and a solid-like disordered open network structure at intermediate temperature. We further discuss the feasibility of realizing a real material with this reversible behavior.
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The properties of glass-forming systems at the Kauzmann temperature
Auteur(s): Kob W.
Conférence invité: 7IDMRCS (, ES, 2013-07-21)
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On the arrangement of sodium atoms around structural units and vibrational properties of a sodium borosilicate glass
Auteur(s): Ispas S., Pedesseau L., Kob W.
Conference: Goldschmidt 2013 (Florence, IT, 2013-08-25)
Ref HAL: hal-01241926_v1
Exporter : BibTex | endNote
Résumé: We have used first principles simulations in order to investigate the properties of a sodium borosilicate glass of composition 3Na2O-B2O3-6SiO2 (NBS). This composition is similar to that of the glass wool used in our daily life. The study was carried up using first principles molecular dynamics within the density functional theory framework as implemented in the VASP code [1]. In this talk, we will present the analysis of the local environments of the three building structural units of the glass network, namely silicon atoms in 4-fold coordination, and boron atoms with 3- or 4-fold coordination. We will also discuss the local distribution of the Na atoms around the basic structural units. Indeed we have identified their preferential neighborhoods and how the nature of network former and its coordination infer on the shape of these preferential regions of Na atoms. The vibrational properties have been equally studied, and the contributions of the various species have been identified. We have found that 3- and 4-fold coordinated boron atoms give rise to distinguished spectral features. Moreover, the partial vibrational density of the 3-fold coordinated B atoms has been found to be a weighted sum of 2 specific contributions so-called 3-fold symmetric coordinated B atoms and asymmetric coordinated B atoms. [1] Kresse & Hafner (1993) PRB 47, 558; Kresse & Furthmüller (1996) Comp.Mater. Sci. 6, 15; Kresse & Furthmüller (1996) PRB 54, 1116
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Probing a Liquid to Glass Transition in Equilibrium
Auteur(s): Kob W., Berthier L.
(Article) Publié:
Physical Review Letters, vol. 110 p.245702 (2013)
PMID 25165938
DOI: 10.1103/PhysRevLett.110.245702
WoS: 000320282600010
101 Citations
Résumé: We use computer simulations to investigate the static properties of a simple glass-forming fluid in which the positions of a finite fraction of the particles have been frozen. By probing the equilibrium statistics of the overlap between independent configurations of the liquid, we find strong evidence that this random pinning induces a glass transition. At low temperatures, our numerical findings are consistent with the existence of a random first-order phase transition rounded by finite size effects.
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The properties of glass-forming systems at the Kauzmann temperature
Auteur(s): Kob W.
Conférence invité: 10th Pacific Rim Conference on Ceramic and Glass Technology (, US, 2013-06-02)
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The properties of a glass-forming system at its Kauzmann temperature
Auteur(s): Kob W.
Conférence invité: 12th International Conference on the Structure of Non-Crystalline Materials (, IT, 2013-07-07)
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