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(317) Production(s) de KOB W.
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New interaction potentials for borate glasses with mixed network formers 
Auteur(s): Sundararaman Siddharth, Huang L., Ispas S., Kob W.
(Article) Publié:
The Journal Of Chemical Physics, vol. 152 p.104501 (2020)
Texte intégral en Openaccess : 
Ref HAL: hal-02563181_v1
DOI: 10.1063/1.5142605
WoS: 000519911600001
Exporter : BibTex | endNote
Résumé: We adapt and apply a recently developed optimization scheme used to obtain effective potentialsfor aluminosilicate glasses to include the network former boron into the interaction parameter set.As input data for the optimization, we used the radial distribution functions of the liquid at hightemperature generated by ab initio molecular dynamics simulations, and density, coordination andelastic modulus of glass at room temperature from experiments. The new interaction potentials areshown to reproduce reliably the structure, coordination and mechanical properties over a widerange of compositions for binary alkali borates. Furthermore, the transferability of these newinteraction parameters allows mixing to reliably reproduce properties of various boroaluminateand borosilicate glasses.
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Determining the Mesh Size of Polymer Solutions via the Pore Size Distribution
Auteur(s): Sorichetti V., Hugouvieux Virginie, Kob W.
(Article) Publié:
Macromolecules, vol. 53 p.2568-2581 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02540128_v1
Ref Arxiv: 1908.01484
DOI: 10.1021/acs.macromol.9b02166
WoS: 000526399500029
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé: In order to determine in polymeric systems the geometrical mesh size ξ, we simulate a solution of coarse-grained polymers with densities ranging from the dilute to the concentrated regime and for different chain lengths. We determine the monomer density fluctuation correlation length ξc from the monomer structure factor as well as the radial distribution function, showing that the identification ξ = ξc is not justified outside of the semidilute regime. In order to better characterize ξ, we compute the pore size distribution (PSD) following two different definitions, one by Torquato et al. and one by Gubbins et al. We find that the mean values of the two distributions, ⟨r⟩T and ⟨r⟩G, display the behavior predicted for ξ by scaling theory, and argue that ξ can be identified with either one of these quantities. This identification allows to interpret the PSD as the distribution of mesh sizes, a quantity which conventional methods cannot access. Finally, we show that it is possible to map a polymer solution on a system of hard or overlapping spheres, for which Torquato’s PSD can be computed analytically and reproduces accurately the PSD of the solution. We give an expression that allows ⟨r⟩T to be estimated with high accuracy in the semidilute regime by knowing only the radius of gyration and the density of the polymers.
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Insight into chemical bonding in oxide glasses from first principles calculations
Auteur(s): Ispas S., Kob W.
Conference: ICG/GOMD 2019 (Boston (MA), US, 2019-06-09)
Ref HAL: hal-04859427_v1
Exporter : BibTex | endNote
Résumé: The use of a first-principles approach makes possible an in-deep study of the chemical bonds existing in oxide glasses and helps to understand how the disorder and/or the composition do affect them.For a series of binary and ternary aluminosilicate and borosilicate glasses, we have computed their electronic properties, as for example the Bader charges and electron localization function. From the examination of the bonds formed between the individual atoms, we have investigated therelationship between the calculated electronic properties and the atoms local environment and, when possible, compared to those of crystal structures with similar compositions.. We have hence obtained more insight into the organization of atoms into well-defined groups in the short range, as well as the reasons that cause some preferential bonding of alkali or alkaline earth atoms.
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Structure and Dynamics of Polymer Composites and Gels: A Simulation Perspective
Auteur(s): Hugouvieux Virginie, Sorichetti V., Kob W.
Conférence invité: Edible Soft Matter – a SoftComp Topical Workshop (Le Mans, FR, 2019-04-17)
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Computer simulations of gels and polymer-nanocomposites
Auteur(s): Sorichetti V., Hugouvieux Virginie, Kob W.
Conférence invité: School on ``Computational methods applied to supercooled liquids, glasses and nanoconfined fluids'' (Buenos Aires, AR, 2019-07-13)
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Simulating Gels and Nanocomposites, May 8-10, 2019, Schluchsee, Germany
Auteur(s): Kob W., Sorichetti V., Hugouvieux Virginie
Conférence invité: IRTG SoMaS Discussion Meeting (Schluchsee, DE, 2019-05-08)
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