DENSITY OF OCCUPIED STATES OF INTERMETALLIC HYDRIDE NIMG2H4

Augmented plane wave band structure calculations using two possible site occupancies for hydrogen atoms were performed; energy bands, total densities of states (DOSs) and partial DOSs at the nickel, magnesium and hydrogen sites ware calculated. X-ray emission spectroscopy allows an experimental determination of the distributions of occupied electronic states in solids. With this method it is possible to obtain the distribution of states around each type of atom present in an alloy or compound with a symmetry consistent with the dipole selection rules. The densities of both the Ni d and the Mg s-p states were investigated by means of (Ni 2p//3/////2) implied by (Ni 3d) and (Mg 1s) implied by (Mg valence band) X-ray transitions. The hydride was found to be an insulator. The nature of the Mg-H, Ni-H and H-H interactions as well as the origin of the gap are discussed and the differences between the structures proposed for the hydride are underlined.