Magnetic and electronic properties of rhodium clusters

We have used all-electron local ~LDA! and nonlocal ~GGA! approximations to the density-functional theory to determine binding energies, equilibrium geometries, vibrational frequencies, and magnetic properties of RhN clusters (N<6). We present careful tests on the Rh2 dimer that compare results as calculated with a large ~18-single Gaussian! and a very large ~23-single Gaussian! basis sets. While the smaller set of Gaussians leads to underconverged results, we find that the large basis set leads to converged results that are also in excellent agreement with the experimental data available for Rh2. The ground state of Rh2 is confirmed to be a quintuplet, the trigonal Rh3 is predicted to be a sextuplet, Rh4 in its tetrahedral configuration is a singlet, Rh5 sextuplet is a square pyramid, and Rh6 septuplet is the octahedron. Results from several excited states are calculated and presented as well. It is found that LDA overestimates the binding energy but that GGA corrects this deficiency and predicts longer bond lengths. @S1050-2947~98!12909-8#