Semirigid vibrating rotor target model for CH4 dissociation on a Ni(111) surface

Abstract

We present a theoretical treatment of the semirigid vibrating rotor target model to study dissociative chemisorption of CH4 at the atop site on Ni(111) surface. In this treatment, the fixed-site approximation is used to study chemisorption of methane on Ni treated as a rigid and locally flat surface. This results in a four-dimensional (4D) theoretical model to treat methane dissociation on Ni. Using parameters from ab initio calculations, an empirical potential energy surface is constructed for the CH4/Ni(111) system over the atop site. A 4D quantum dynamics calculation using the time-dependent wave-packet method is carried out on this potential energy surface. Our calculation shows that the dissociation probability of methane is an increasing function of kinetic energy, and the C–H stretching vibration significantly enhances the dissociation. The dissociation probability has a strong dependence on the initial orientation of the molecule. Reasonably good agreement is found between the current theoretical calculation and experimental results.