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Etude des propriétés structurales, électroniques et vibrationnelles des verres et des nanostructures par simulation ab-initio
(11) Production(s) de l'année 2019
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New interaction potentials for alkali and alkaline-earth aluminosilicate glasses 
Auteur(s): Sundararaman Siddharth, Huang Liping, Ispas S., Kob W.
(Article) Publié:
The Journal Of Chemical Physics, vol. 150 p.154505 (2019)
Texte intégral en Openaccess : 
Ref HAL: hal-02121330_v1
DOI: 10.1063/1.5079663
WoS: 000465442100042
Exporter : BibTex | endNote
7 Citations
Résumé: We apply a recently developed optimization scheme to obtain effective potentials for alkali andalkaline-earth aluminosilicate glasses that contains lithium, sodium, potassium, or calcium asmodifiers. As input data for the optimization, we used the radial distribution functions of theliquid at high temperature generated by means of ab initio molecular dynamics simulations anddensity and elastic modulus of glass at room temperature from experiments. The new interactionpotentials are able to reproduce reliably the structure and various mechanical and vibrationalproperties over a wide range of compositions for binary silicates. We have tested these potentialsfor various ternary systems and find that they are transferable and can be mixed, thus allowing toreproduce and predict the structure and properties of multi-component glasses.
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Vibrational properties of sodosilicate glasses from first-principles calculations
Auteur(s): Kilymis D., Ispas S., Hehlen B., Peuget S., Delaye Jean-Marc
(Article) Publié:
Physical Review B, vol. 99 p.054209 (2019)
Texte intégral en Openaccess : 
Ref HAL: hal-02043157_v1
DOI: 10.1103/PhysRevB.99.054209
WoS: 000459221700002
Exporter : BibTex | endNote
5 Citations
Résumé: The vibrational properties of three sodosilicate glasses have been investigated in the framework of density functional theory. The pure vibrational density of states has been calculated for all systems and the different vibrational modes have been assigned to specific atoms or structuralunits. It is shown that the Na content affects several vibrational features as the position and intensity of the R band or the mixing of the rocking and bending atomic motions of the Si-O-Si bridges. The calculated Raman spectra have been found to agree with experimental observations and their decomposition indicated the dominant character of the non-bridging oxygen contribution on the spectra, in particular for the high-frequency band, above 800 cm −1 . The decomposition of the high-frequency Raman feature into vibrations of the depolymerized tetrahedra (i.e. Q n -units) has revealed spectral shapes of the partial contributions that cannot be accounted for by simple Gaussians as frequently assumed in the treatment of experimentally obtained Raman spectra.
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