Chemisorption of atomic hydrogen on rhodium: An ab initio cluster-model approach

Interaction of atomic hydrogen with cluster models simulating the Rh(111) surface has been studied at the ab initio SCF level using relativistic non-empirical pseudopotentials and moderately large basis sets. From the bonding parameters, it is seen that chemisorption on the threefold open position is five times more favoured than on the threefold eclipsed one, and the bonding picture is rather different for both active sites. Since two different kinds of adsorbed hydrogen atoms should exist according to various experimental techniques, the present work adds further evidence to the existence of these two types of adsorption and reports some structural parameters which can help to a more detailed characterization in the near future.