Dynamics of the chemisorption of hydrogen on the Fe(001) surface

The binding energy curves of the H-Fe(001) system have been computed within a tight-binding approach in the extended Hückel approximation, and have been used to build a LEPS potential-energy surface for H2-Fe(001). The results indicate that the adsorption is exothermic with respect both to atomic and molecular hydrogen. The LEPS potential was then employed in stochastic quasi-classical trajectory calculations to study the dynamics of H2 adsorption. We have found that the dissociative adsorption probability Pa increases for increasing values of the collision and total energies, according to steep S-shaped curves; the H2 translational energy is more effective than the rovibrational component in overcoming the adsorption barrier; Pa decreases on increasing the polar angle of incidence, and a good trend is observed for normal energy scaling: Pa is significantly influenced by the corrugation of the (001) surface.