Quantum dynamics of dissociative adsorption of H2 and D2: The time-dependent wave packet method

Abstract

A time-dependent quantum wave packet method was used to study the dynamics of dissociative adsorption of H2 and D2 on a flat and static surface. The molecule-surface interaction is described using a modified London-Eyring-Polanyi-Sato (LEPS) type potential for the H2/Ni(100) system. The three-dimensional (3-D) dissociation probabilities were calculated for different initial rovibrational states as a function of initial incident energies. Our results show that the dissociation of the diatomic rotational states whose quantum numbers satisfyj+m = odd is forbidden at low energies for the homonuclear Hz and D2 due to the selection rule. The effect of the rotational orientation of diatoms on adsorption predicts that the in-plane rotation (m = j) is more favorable for dissociation than the out-of-plane rotation (m = 0). Enhanced dissociation for vibrationally excited molecules and the significant enhancement of the dissociation probability of H2 when compared to D2 were explained reasonably in terms of quantum mechanical zero-point energies, the tunneling effect and the reflection from an activation barrier.