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

Abstract

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 P_a 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; P_a decreases on increasing the polar angle of incidence, and a good trend is observed for normal energy scaling: P_a is significantly influenced by the corrugation of the (001) surface.