Structure Determination of Small Metal Clusters by Density-Functional Theory and Comparison with Experimental Far-Infrared Spectra

The far-infrared vibrational spectra for charged vanadium clusters as well as charged and neutral niobium clusters have been measured size specifically using farinfrared multiple photon dissociation. The ground state energy and vibrational spectra of a large number of stable and metastable structures for each of these sizes and systems have also been calculated using densityfunctional theory (DFT). A comparison of the calculated vibrational spectra with those obtained in the experiment allows us to deduce the cluster size specific atomic structures. Our results suggest that sometimes there is one unique atomic structure, while in other cases the experiment might observe several isomers. A comparison of the results for cationic vanadium and cationic niobium and the results for neutral niobium allows us to explore the differences between the different systems, and clusters with different charges.