Eley-Rideal reaction dynamics between O atoms on β-cristobalite (100) surface: a new interpolated potential energy surface and classical trajectory study

Abstract

We present a theoretical study of the collisions of atomic oxygen with O-precovered b-cristobalite (100) surface. We have constructed a multidimensional potential energy surface for the O2/b-cristobalite (100) system based mainly on a dense grid of density functional theory points by using the interpolation corrugation reducing procedure. Classical trajectories have been computed for quasithermal (100-1500 K) and state-specific (e.g., collision energies between 0.01-4 eV) conditions of reactants for different O incident angles. Atomic sticking and O2(adsorbed) formation are the main processes, although atomic reflection and Eley-Rideal (ER) reaction (i.e., O2 gas) are also significant, depending their reaction probabilities on the O incident angle. ER reaction is enhanced by temperature increase, with an activation energy derived from the atomic recombination coefficient (gamma_O(0,T)) equal to 0.24±0.02 eV within the 500-1500 K range, in close agreement with experimental data. Calculated gamma_O(0,T) values compare quite well with available experimental gamma_O(T) although a more accurate calculation is proposed. Chemical energy accommodation coefficient beta_O(T) is also discussed as a function of ER and other competitive contributions.