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

We present a theoretical study of the collisions of atomic oxygen with O-precovered beta-cristobalite (100) surface. We have constructed a multidimensional potential energy surface for the O-2/beta-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 and 4 eV) conditions of reactants for different O incident angles (0(v)). Atomic sticking and O-2(adsorbed) formation are the main processes, although atomic reflection and Eley-Rideal (ER) reaction (i.e., 02 gas) are also significant, depending their reaction probabilities on the 0 incident angle. ER reaction is enhanced by temperature increase, with an activation energy derived from the atomic recombination coefficient (gamma(O)(0(v) = 0 degrees, T)) equal to 0.24 +/- 0.02 eV within the 500-1500 K range, in close agreement with experimental data. Calculated gamma(O)(0(v) = 0 degrees, 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. (C) 2009 Elsevier B.V. All rights reserved.