Résumé
Silicate glasses possess a central role in glass technology due to their multiple applications ranging from optical devices to the immobilization of nuclear waste. Raman spectroscopy is a key method for the investigation of their structure and the study of their properties. However, the inherent structural disorder found in glasses results in very broad and overlapping peaks in their spectra. In this context, an accurate theoretical modeling of the spectra can be proven to be invaluable in order to optimize their performance and tailor their fabrication method to match requirements for future applications. In this work, we present results on binary sodo-silicate glasses [xNa2O- (1-x)SiO2], which have been prepared by combining classical and ab-initio Molecular Dynamics. The Raman spectra (polarized and unpolarized), as well as the IR spectra, have been obtained using the Quantum Espresso package [1] in the GGA framework by employing norm-conserving pseudopotentials. Calibration runs have been carried out on the crystalline α-quartz and Na2SiO3 systems in order to optimize the choice of pseudopotentials. Concerning the glasses under study, we focused on the effect of local structural units, such as Q-species and their interconnection, alongside the role of sodium atom content in order to assign the corresponding bands. The initial results show very good agreement with previous theoretical and experimental spectra [2-5], while the ongoing decomposition relative to the exact contributions from each of the structural units of the glasses is expected to provide insight to the interpretation of the experimental spectra.References[1] P. Gianozzi et al., J. Phys.: Condens. Matter 21, 395502 (2009).[2] S. Ispas, N. Zotov, S. de Wispelaere, W. Kob, J. Non-Cryst. Solids 351, 1144 (2005).[3] N. Zotov, H. Keppler, Phys. Chem. Minerals 25, 259 (1998).[4] B. Hehlen, D.R. Neuville, J. Phys. Chem. B 119, 4093 (2015).[5] B.O. Mysen, J.D. Frantz, Contrib. Mineral. Petrol. 117, 1 (1994).