Electronic structure of the rare-earth superstoichiometric dihydride GdH2.25

With the WIEN2k simulation code, ab initio calculations of electronic structure and of equilibrium properties for the superstoichiometric rare-earth dihydride GdH2.25 using the full-potential linearized augmented plane-wave (FP-LAPW) method within density functional theory (DFT) in generalized gradient approximation (GGA) were performed. The lattice parameter, bulk modulus, pressure derivative, density of states (DOS) and energy band structures were determined. The GGA-optimized lattice parameter agrees much better with the experimental findings than the local density approximation (LDA) one. The non-negligible electronic DOS at Fermi level confirms that GdH2.25 has a metallic character. The Fermi energy (E-F) falls at a level where most of the states are rare-earth 5d conduction states while negligible contributions of both interstitial (tetrahedral and octahedral) H s states are observed near E-F. It is found that hybridization exists between s electronic orbital of both interstitial H atoms and d electronic orbitals of Gd.