Methane dissociation on Ni(111): Reaction probabilities using direct and initial state selected approaches

We present two strategies for obtaining initial state selected reaction probabilities employing the multi-configurational time-dependent Hartree approach. The standard approach consists in building a wave function representative of the initial state of the reactants and propagating the wave into the strong interaction region. Reversely, a complete set of quantum states can be built in the strong interaction region and propagated outwards, obtaining the reaction probability from flux correlation functions. These two schemes are compared in our paper for the particular case of gas/surface reactions. In order to do this, we have computed initial state-selected reaction probabilities for the CH4 + Ni(111) dissociative adsorption reaction. The system is modeled by considering exclusively normal incidence and treating the molecule as quasidiatomic H-X, with X=CH3. Results are compared with previous standard wave packet calculations analyzing the role of vibration and rotation in the molecule as well as the surface temperature. (C) 2011 Elsevier B.V. All rights reserved.