Electronic structure of lithium amide

Abstract

The electronic structure of the insulator lithium amide (${\mathrm{LiNH}}_{2}$), which is a lightweight complex hydride being considered as a high-capacity hydrogen storage material, is investigated by N $1s$ soft x-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The XES and XAS spectra show a band gap between the valence and conduction bands. The valence band in the XES spectrum consists of three peaks, which extend up to $~$$\ensuremath{-}8$ eV from the valence band top. The band calculation within the local-density approximation (LDA) for ${\mathrm{LiNH}}_{2}$shows energetically separated three peaks in the occupied N $2p$ partial density of states (pDOS) and the band gap. The energy distribution of three peaks in the XES spectrum agrees with that in the calculated pDOS except for the peak at the highest binding energy, which is attributed to the strongly hybridized state between N $2p$ and H $1s$. The XES experiment has clarified that the strongly hybridized state with H $1s$ in ${\mathrm{LiNH}}_{2}$is located at binding energy higher than that of the LDA calculation, while the overall feature of the electronic structure of ${\mathrm{LiNH}}_{2}$experimentally obtained by XES and XAS is consistent with the calculated result.