Six-dimensional quantum dynamics of dissociative chemisorption of H2 on Cu(100)

Abstract

The dissociative chemisorption of H2 on Cu(100) has been studied using a six-dimensional wave packet method. All molecular degrees of freedom are treated quantum mechanically, with no dynamical approximations. The potential-energy surface used is an analytical fit to calculations employing density functional theory (DFT), using the generalized gradient approximation (GGA) and a slab representation of the metal surface. The dependence of the reaction probability on normal incidence energy has been obtained for both (v=0, j=0) and (v=1, j=0) H2. Comparison to experiment suggests that, on average, the DFT method overestimates the barriers to dissociation by ∼0.15 eV for H2+Cu(100). In broad agreement with experiments on H2+Cu(111) and H2+Cu(110) the calculations show large vibrational inelasticity. A prediction of the survival probability of (v=1, j=0) H2 as a function of incidence energy is also presented. The measurement of this quantity is now feasible and should provide another sensitive test of the DFT potential-energy surface.