A Molecular Dynamics Study of the Effect of the Incidence Angle on the Dissociation Probability of H2 on Pt(111)

Abstract

Dissociative adsorption processes of hydrogen molecules on a platinum surface were simulated by a molecular dynamics (MD) method. The effect of the incidence angle of the impinging gas molecules on the dissociation probability was analyzed. The embedded atom method (EAM) was used to construct an interaction potential between the gas molecule and the Pt(111) surface. Initially, the effect of the motions of atoms or molecules (dynamic effects) on the dissociation probability was studied. It showed that dynamic effects on the dissociation phenomena are very large for adsorption at the top site. A number of MD simulations of H2 or D2 molecules impinging on a Pt(111) surface were also carried out, with varying initial orientations and rotational energy of the molecule, and differing collision locations on the surface. The results were averaged and the effects of the isotopic nature, incident angle, and translational energy of the adsorbate were analyzed. The results were also compared to those obtained from molecular beam experiments to check the validity of the simulations. This comparison showed that the dependences of the dissociation probability on translational energy and incident angle roughly agree with experiments.