Aspherical and covalent bonding character of d electrons of molybdenum from synchrotron x-ray diffraction

Abstract

The occupancies and spatial distribution of electrons for 4d-orbitals in pure molybdenum have been experimentally determined by a charge density study from synchrotron radiation x-ray powder diffraction. There are valence charge density maxima in interatomic positions indicating bond formation. The electron deficiencies of Γ 12 orbitals were visualized in the observed static deformation density. An electron deficiency of ∼0.5 was observed from the orbital population analysis through multipole refinement. The occupancies and spatial distribution have also been calculated by a density functional theoretical calculation using WIEN2k packages for comparison. The observed features agree well with the theoretical study. In addition, the observed charge density has more covalent bonding character than the theoretical one. The present study confirms that a state-of-the-art x-ray charge density study can reveal the spatial structure of d-electrons in 4d-system.