Quantum dynamics of the dissociation of H2 on Rh(111)

The dissociative adsorption of H2 on Rh(111) has been studied by high-dimensional quantum calculations using a coupled channel scheme. The potential energy surface was derived from ab initio total energy calculations using density functional theory together with the generalized gradient approximation to describe exchange-correlation effects. Experimentally, at high kinetic energy a step in the dissociative adsorption probability as a function of kinetic energy has been observed [M. Beutl et al., Surf. Sci. 429, 71 (1999)] which has been attributed to the opening up of a new adsorption channel. This feature in the dissociation probability is reproduced in the calculations for H2 molecules initially in the ro-vibrational ground state but it is not related to the opening up of an additional dissociation channel. Instead, it is caused by purely dynamical effects. In addition, rotational effects in the H2 dissociation are addressed.