Study of the structural and electronic properties of Rh(N) and Ru(N) clusters (N < 20) within the density functional theory.

Using the density-functional theory (DFT) with the generalized gradient approximation to exchange and correlation, we compute the geometries, electronic structure, and related properties of free-standing rhodium and ruthenium atomic clusters with sizes below 20 atoms. We explore different structural and spin isomers per size, for which we determine the interatomic distances, binding energy, magnetic moment, HOMO-LUMO gap, and electric dipole moment. For many sizes, different implementations of DFT predict different properties for the lowest-energy isomers, thus illustrating the complex nature of these 4d transition metal elements at the nanoscale. We discuss our results for rhodium clusters in the context of recent electric deflection measurements.