Electronic Structure of Vanadium-Hydrogen Clusters
The electronic structure and total energy of clusters of vanadium atoms of various sizes, both with and without a hydrogen atom, have been calculated using the self-consistent multiple scattering Xα method. The smallest cluster considered, V4, represents the four vanadium atoms nearest the tetrahedral interstitial site in the body-centered-cubic lattice. Recent theoretical work by Abell has ascribed to this and analogous isolated four-atom clusters of the other Group V metals, an inherent instability with respect to a Jahn-Teller distortion. This instability arises from the existence of a two-fold degenerate electronic state in the isolated cluster. In this theory, the presence of hydrogen stabilizes the Jahn-Teller distortion. We have investigated this by performing our calcula-tions for hydrided and unhydrided clusters, for both the undistorted and distorted structures, with the aim of identifying states near the Fermi level whose energies may be especially sensitive to the distortion.