Neutral self-defects in a silica model: A first-principles study

We present a statistical study of silicon and oxygen neutral defects in a silica glass model. This work is performed following two complementary approaches: first-principles calculations and empirical potential molecular dynamics. We show that the defect formation energies and structures are distributed and that the energy distributions are correlated with the local stress before the defect formation. Combining defect energies calculated from first principles and local stresses from empirical potential calculations in undefected silica, we are able to predict the formation energy distributions in larger systems, the size of which precludes the use of ab initio methods. Using the resulting prediction we will show that the cell size used in our modeling contains all the formation energy fluctuations needed to describe a real glass.