First-principles investigation of LaMg(2)Ni and its hydrides

Using first-principles density functional theory calculations, the electronic structures of LaMg(2)Ni and its hydrides LaMg(2)NiH(4.5) (intermediate phase) and LaMg(2)NiH(7) (fully hydrogenated phase), as well as the H adsorption on LaMg(2)Ni (100) surface were investigated. For comparision, the atomic bonding characteristics of Co- and Pd-doped LaMg(2)Ni, LaMg(2)NiH(4.5) and LaMg(2)NiH(7) compounds were also studied. Our aim is to provide new insights into the hydrogenation of LaMg(2)Ni. The results show that the metallic intermediate hydride LaMg(2)NiH(4.5) with Ni–H covalent bonds may act as the precursor state from the host compound LaMg(2)Ni to the full hydride LaMg(2)NiH(7). Upon LaMg(2)Ni hydrogenation, the suppression of Mg–Ni and Ni–H interactions as well as the formation of La-H bonds favors for LaMg(2)Ni–H formation.