Structure and electronic properties of RuSi, OsSi, RhSi, ReSi and IrSi

Abstract RuSi, OsSi, RhSi, ReSi and IrSi in different phases have been investigated by means of ab initio techniques within the hybrid functional. RuSi and OsSi have the cubic (space group P2 1 3, #198) structure and display semiconducting properties, while the conducting high-temperature cubic phase (space group Pm3m, #221) is sizably higher in energy. The ground state for RhSi and IrSi is the orthorhombic (space group Pnma, #62) structure, while for ReSi it is monoclinic (space group P2 1 /c, #14) with the cubic phase (space group P2 1 3, #198) to be higher in total energy. The Dirac nodes and cones as well as crossing bands with linear dispersion are found for RhSi, ReSi and IrSi in the orthorhombic phase. These monosilicides in the monoclinic phase can be viewed as gapless semiconductors except for IrSi with the band gap of 0.23 eV.