Quantum and classical studies of the dissociation dynamics of H2 and its isotopes on Ni

Abstract

A two-dimensional quantum mechanical model is used to study the dissociative adsorption of H2 and its heavier isotopes on Ni(100). Dissociation probabilities are computed as a function of molecular kinetic energy for H2 , D2 , T2 , and a hypothetical heavier isotope. It is demonstrated how the variation of the zero point energy with mass strongly influences the dynamics. A qualitative agreement with recent experimental results for H2 and D2 is obtained. Quasiclassical trajectory calculations are performed for the same systems. By comparison with the exact quantum calculations, the classical probabilities for H2 and D2 are shown to be too large at low kinetic energies. For molecules heavier than T2 , classical dynamics are shown to be adequate. The sources of error in the classical simulations are discussed.