Density Functional Study of the Interaction of Palladium Clusters with Hydrogen and CHx Species

Abstract

Structures and energies of Pdn clusters, with n ranging from 2 to 7, were determined through density functional theory. The calculations were performed adopting the B3LYP functionals to calculate the exchange and correlation energy, the effective core potential basis set of Hay and Wadt for the core electrons of palladium (double-ζ on the valence electrons), and the Dunning/Huzinaga full double-ζ basis set for the other atoms. It was found that Pdn optimized structures are almost regular polyhedrons, all stable as triplets. The calculated geometries were an isosceles triangle for Pd3, a distorted tetrahedron for Pd4, a bipyramid with triangular base for Pd5, a distorted octahedron for Pd6, and a bipyramid with pentagonal base for Pd7. The interaction of these clusters with atomic hydrogen in terms of structure and energy was also considered. All structures are stable with the hydrogen lying outside of the cluster, preferably 3-fold coordinated. A maximum of the hydrogen bond energy was found for a cluster...