Diffusion of a hydrogen atom on the Pd(1 1 1) surface: quantum transition state wave packet approach

The self-diffusion of a hydrogen atom adsorbed on the (1 1 1) surface of palladium is investigated at various temperatures. The potential energy surface for the adsorbate–substrate interaction is determined from ab initio calculations. A recently proposed quantum transition state theory is used for calculating the hopping rate of the adsorbate. Some evidence is observed for different regimes of the diffusion at different temperatures. The influence of the dimensionality of a model on the diffusion coefficient is examined as well and it is found that the diffusion coefficient can be overestimated by one order of magnitude at very low temperatures.