Résumé
To investigate the structural mechanisms underlying plastic behaviour and polyamorphism in silica glasses (v-SiO2), we conducted Molecular Dynamics (MD) simulations using various computational approaches. A recent Density Functional Tight-Binding study demonstrated that structural transformations between LDA and HDA states in v-SiO2 occur via percolation transitions, which can also explain certainmechanical properties of v-SiO2. To further study clusters and percolation networks, we used the classical MD simulation approach, whichallowed a significant improvement in statistics and access to larger length scales (up to 12 nm). The percolation transitions were successfully reproduced, and clusters spanning several orders of magnitude enabled the extraction of scaling laws for properties like mass, correlation length, and order parameter. The scaling of these properties is linked to critical exponents and the fractal dimensionality of clusters, definingthe universality class of the transition. Our analysis of the SiOn-SiOm connectivities (n,m=4,5,6) reveals a single universality class and provides a framework to detect amorphous-amorphous transformations upon compression. We have extended this work by simulating liquid SiO2 to track the evolution of the transitions with temperature and pressure, potentially allowing us to construct a metastable "phase" diagram for v-SiO2.