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(317) Production(s) de KOB W.
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Etude ab initio des mécanismes d'altération par l'eau des verres nucleaires
Auteur(s): Geneste G., Bouyer F., Ispas S., Kob W.
(Affiches/Poster)
GDR-DFT (Cap d'Agde, France, FR), 2005-05-18 |
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Développement de potentiels classiques pour la silice liquide
Auteur(s): Carre Antoine, Ispas S., Kob W.
(Affiches/Poster)
GDR - DFT (Cap d'Agde, France, FR), 2005-05-18 |
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Computer Simulations of Supercooled Liquids and Glasses
Auteur(s): Kob W.
Chapître d'ouvrage: Handbook Of Materials Modeling, vol. p.2823-2828 (2005)
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Glassy Materials and disordered solids
Auteur(s): Binder K., Kob W.
Ouvrage: World Scientific (2005) |
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Atomistic simulation of glasses-Strategic considerations and review of slective results
Auteur(s): Fotheringham U., Binder K., Horbach J., Kob W.
Conférence invité: Inconnu (, FR, 2005)
Actes de conférence: Glass Science Technology, vol. 78 p.203-211 (2005)
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Vibrational properties of a sodium tetrasilicate glass: Ab initio versus Classical Force Fields 
Auteur(s): Ispas S., Zotov N., De wispelaere S., Kob W.
Conférence invité: CONCIM International Conference on Non-Crystalline Inorganic Materials (Bonn, DE, 2003-04-08)
Actes de conférence: Journal of non-crystalline solids, vol. 351 p.1144-1150 (2005)
Texte intégral en Openaccess : 
Ref Arxiv: cond-mat/0306332
Ref. & Cit.: NASA ADS
Résumé: We have determined the vibrational properties of a sodium tetrasilicate(Na$_{2}$Si$_{4}$O$_{9}$) glass model generated by molecular dynamicssimulations. The study has been carried out using a classical valence forcefields approach as well as an {\it ab initio} approach in the framework of thedensity functional theory. The total and partial vibrational densities ofstates (VDOS) are presented, as well as some characteristics of the vibrationalmodes (participation ratios, correlation lengths). For the low-frequency bandsbelow 500 cm${}^{-1}$, we find that the shapes of the two calculated VDOS aswell as those of their corresponding partial VDOS are quite similar. For theintermediate- and high-frequency ranges, we observe larger discrepanciesbetween the two calculations. Using the eigenmodes of the dynamical matrix wealso calculate the polarized Raman spectra within the bond-polarizabilityapproximation. We find an overall agreement between the calculated parallelpolarized (VV) Raman spectra and the corresponding experimental spectrum.Regarding the perpendicular depolarized (VH) Raman spectrum, the comparison ofthe calculated spectra to the experimental data indicates a need for anadjustment of the VH bond-polarizability parameters.
Commentaires: 17 pages, 4 EPS figures, submitted to J. Non. Cryst.-Sol., corrected version following referee's comments
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First-principles molecular-dynamics simulations of a hydrous silica melt: Structural properties and hydrogen diffusion mechanism
Auteur(s): Poehlmann Markus, Benoit Magalie, Kob W.
Conference: (, FR, 2004)
Actes de conférence: Technical Proceedings of the 2004 NSTI Nanotechnoloy Conference and Trade Show, vol. p.73-76 (2004)
Texte intégral en Openaccess :
Ref HAL: hal-00133199_v1
Ref Arxiv: cond-mat/0403253
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We use {\it ab initio} molecular dynamics simulations to study a sample of liquid silica containing 3.84 wt.% H$_2$O.We find that, for temperatures of 3000 K and 3500 K,water is almost exclusively dissolved as hydroxyl groups, the silica network is partially broken and static and dynamical properties of the silica network change considerably upon the addition of water.Water molecules or free O-H groups occur only at the highest temperature but are not stable and disintegrate rapidly.Structural properties of this system are compared to those of pure silica and sodium tetrasilicate melts at equivalent temperatures. These comparisons confirm the picture of a partially broken tetrahedral network in the hydrous liquid and suggest that the structure of the matrix is as much changed by the addition of water than it is by the addition of the same amount (in mole %) of sodium oxide. On larger length scales, correlations are qualitatively similar but seem to be more pronounced in the hydrous silica liquid. Finally, we study the diffusion mechanisms of the hydrogen atoms in the melt. It turns out that HOSi$_2$ triclusters and SiO dangling bonds play a decisive role as intermediate states for the hydrogen diffusion.
Commentaires: 25 pages, 18 figures. submitted
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