Hydrogen-induced insulating state accompanied by interlayer charge ordering in SmNiO₃

The effect of hydrogen doping on the crystal structure and the electronic state of SmNiO3 is investigated by means of density functional theory with a combinatorial structure-generation approach. While 100% of hydrogen doping per Ni atom has been supposed to be responsible for the experimentally observed insulating phase, we found that 50% of hydrogen doping results in an outstandingly stable atomic structure showing the insulating property after the structural relaxation was performed while imposing a ferromagnetic configuration. The stable crystal structure shows the peculiar layered pattern of charge disproportionation of Ni2+ and Ni3+ valences together with the strong Jahn-Teller distortion that causes the eg orbital state splitting and opens the band gap.