Molecular dynamics study of H2 dissociation on H-covered Pd(100)

We employ classical molecular dynamics calculations based on density-functional theory molecule-surface interaction potentials to study H-coverage effects on H-2 dissociative adsorption on Pd(100). In contrast with one of the basic assumptions of the widely used Langmuir model, we have found that a single isolated H-vacancy is enough to spontaneously dissociate low-energy H-2 molecules on H-covered Pd(100). We also show that for a given initial coverage (e.g., Theta=1/2), the dissociative adsorption probability of low-energy H-2 molecules can vary by a factor of five depending on the particular arrangement of the H adatoms on the surface.