Geometries, stabilities, electronic and magnetic properties of small PdnIr (n = 1–8) clusters from first-principles calculations

Abstract

The geometrical structures, relative stabilities, electronic and magnetic properties of small PdnIr (n = 1–8) clusters have been systematically investigated using density functional theory at the B3PW91 level. The optimised geometries show that the lowest-energy structures of PdnIr clusters prefer a three-dimensional configuration. The relative stability of these clusters was examined by analysis of the binding energies per atom, fragmentation energies, the second-order difference of energies and the HOMO–LUMO energy gaps as a function of cluster size. The obtained results exhibit that the Pd2Ir, Pd3Ir and Pd5Ir clusters are more stable than their neighbouring clusters. The energy gap of the Pd2Ir cluster is the largest of all the clusters (2.258 eV). In addition, the charge transfers, vertical ionisation potentials, vertical electron affinities and chemical hardness were calculated and discussed. The magnetism calculations indicate that the total magnetic moment of PdnIr clusters is mainly localised on the iridium atom for Pd1–6Ir clusters. Meanwhile, the 5d orbital plays the key role in the magnetic moment of the iridium atom.