Ab initio molecular dynamics simulations of oxygen-deficient centers in pure and Ge-doped silica glasses: Structure and optical properties

We have calculated the optical absorption (OA) bands of oxygen-deficient centers (ODC(I) type) in pure and germanium (Ge)-doped silica using the density functional theory-plane waves (DFT-PW) method connected to the Kubo-Greenwood formalism. A statistical approach is used in order to reproduce the complex nature of amorphous systems. This preliminary study shows that calculated locations of the OA bands of both Si-ODC and Ge-ODC accurately agree with experimental data in spite of the well-known underestimation of the gap of insulators using DFT. (c) 2006 Elsevier B.V. All rights reserved.