Though brittle, silicate glasses undergo plastic deformation at the microscopic scale.

The Mechanical Response of a Model Silica Glass is studied extensively at the submicrometer scale, with the help of atomistic simulations. The analysis of the response to a hydrostatic compression is compared to recent experimental results. The irreversible behaviour and the variation of intertetrahedral angles is recovered. It is shown that the atomistic response is homogeneous upon compression, in opposition with the localization along shear bands occuring during shear deformation with constant volume. Moreover, the Bulk Modulus anomaly is interpreted as due to a succession of such homogeneous but irreversible atomic rearrangements.