This thesis discusses the mechanical and vibrationnal behaviour of silica glasses. Here, classical molecular dynamics methods are used to model a glass using asmoothed and truncated BKS potential. The model is validated through structural and dynamical comparisons with X-rays and neutrons scattering experiments. The numerical sample in mechanically loaded, and the response to a strain (hydrostatic compression, shear at constant volume or pressure in the elastic domain and beyond) is studied in the frame of the classical theroy of elasticity. The use of classical molecular dynamics gave us a microscopic approach via the non-affine displacement study, to explain some macroscopic behaviour, which is not yet developed much in literature. In particular, we illustrated the origins of the bulk modulus anomaly of silica glasses because of its micro-plastic behaviour. we also obtained the yield surface (boundary between elastic and plastic behaviour) of silica glasses. Moreover, Raman spectroscopy is performed under diamond anvil cell, and the results were compared with the Raman spectra of numerically loaded glasses. At last; we discussed the validity of theoritical description and the limitation.
Vibrationnal modes and mechanical behaviour of silicia glasses : a numerical study and RAMAN spectroscopy