lectron Spectroscopic Studies of Metal-Hydrogen Bonding

-Calculation of electronic structures of ScH₂, NiH₂, YH₂ and PdH₂ by the Xα method-

Abstract

The electronic structures of ScH₂, NiH₂, YH₂, and PdH₂ with the cubic fluorite structure have been calculated using the discrete variational (DV) -Xα method. Clusters studied were [Me₆H₈] ⁴⁺ and [Me₄H₈] (Me : metallic atom). The level profiles of the [Me₄H₈] clusters revealed that Me-H bonding levels are located more than 4 to 7.5eV below the E_F level. The results are generally in good agreement with UPS spectra previously observed for the Me-H system. The charge states were determined to be 1.2±0.4 for Me atoms and -0.6±0.2 for H atoms. The charge on the H atoms decreases as the mass of the Me atom increases in a particular group of the Periodic System. This is consistent with prediction from Pauling's electronegativity. The calculated level profiles and charge states are used to predict XPS spectra of the valence-band region. Analyses of spectral patterns showed that a photopeak of the Me-H bonding levels disappears as the number of d electron is increased.