STRUCTURAL CHARACTERIZATION OF NIOBIUM-CLUSTER ANIONS FROM DENSITY-FUNCTIONAL CALCULATIONS

We did an extensive search for the lowest-energy isomers of Nb-n(-) (n =3-8) with a local-spin-density method. We report the calculated optim um geometries for various cluster isomers, and their vibrational frequ encies and electron binding energies. We describe two simple ways to a ccount for final-state effects on electron binding energies, based on Slater's transition state method, which yield results consistent with one another and with experiment.