Oxygen Adsorption on β-Quartz Model Surfaces: Some Insights from Density Functional Theory Calculations and Semiclassical Time-Dependent Dynamics

The O/beta-quartz interaction is described by combining our time-dependent semiclassical approach to atom-molecule/surface scattering with first-principles electronic structure calculations at the DFT (PBE0) level of accuracy. In particular, the O, O-2 interaction potentials with an on-top Si atom and its nearest O atom both localized over three different silica clusters have been calculated as a function of the oxygen-silica approaching distance. The calculated DFT potential energy surface has been used in semiclassical trajectory calculations to investigate the sticking and inelastic reflection of oxygen atoms from a model beta-quartz surface. The collisional mechanism, including the role played by the phonon dynamics, is brought to light and accurate sticking probabilities are calculated at five impact energies in the range [0.05-0.8] eV and T-S = 1000 K. The different catalytic response of beta-quartz and beta-cristobobalite to the atomic oxygen flux is also discussed and highlighted.