Density functional theory study of the interaction of H2 with rhodium clusters

The adsorption for H atoms on the Rh-n cluster has been systematically investigated by density functional theory. The result indicates that the lowest energy structures of Rh-n H-2 are generated with H atoms being adsorbed on the lowest energy structure of Rho clusters, and the lowest energy structures of Rh-n clusters are not changed by adsorbing H atoms. The total magnetic moment is affected by average bond distance. The chemisorption of H atoms on Rh-n clusters belongs to dissociative adsorption. When H-2 is absorbed on the Rh-n clusters, the stability and chemical action of corresponding clusters are dramatically increased. The second order difference indicates 4 is magic number in Rh-n H-2 and Rh-n clusters. Among various possible adsorption sites, bridge site is energetically preferred for n <= 5. The hollow site adsorption appears for n >= 6.