Structure simulation of silica glasses: approach to CVD

We describe a new way to simulate the structure of vitreous silica. Using a n improved semi-empirical code, we simulate the condensation of SiO2 molecu les (typically 27 SiO2 molecules) into aggregates, stopping the computation at the first local total energy minimum. The structure of these aggregates appears to be very disordered with a distribution of coordination number, angle and bond length. It is representative of small particles obtained in any chemical vapour deposition process.