Ab initio approach of the hydrogen insertion effects on the magnetic properties of $ {bf ScFe_2} $

The electronic and magnetic structures of $ {rm ScFe_2} $ and of its dihydride $ {rm ScFe_2H_2} $ are self-consistently calculated within the density functional theory (DFT) using the all electron augmented spherical wave (ASW) method with the local spin density approximation (LSDA) for treating effects of exchange and correlation. The results of the enhancement of the magnetization upon hydrogen insertion are assessed within an analysis of the chemical bonding properties from which we suggest that both hydrogen bond with iron and cell expansion effects play a role in the change of the magnitude of magnetization. In agreement with average experimental findings for both the intermetallic system and its dihydride, the calculated Fermi contact terms $H_{FC}$ of the $^{57}$Fe Mossbauer spectroscopy for hyperfine field, at the two iron sites, exhibit an original inversion for the order of magnitudes upon hydriding.