Ab initio study of the nature of the chemical bond and electronic structure of the layered phase Ca10(Pt4As8)(Fe2As2)5 as a parent system in the search for new superconducting iron-containing materials

Ab initio calculations were used in a detailed study of chemical bonding and electronic structure of the recently discovered superconducting tetragonal phase Ca10(Pt4As8)(Fe2As2)5 (TC 25 K). The Ca10(Pt4As8)(Fe2As2)5 phase is metal-like, mainly due to the Fe3d states of the (Fe2As2)5 blocks. The electronic spectrum of the (Pt4As8) blocks is similar to a semi-metal with very low density of states at the Fermi level. Chemical bonding in Ca10(Pt4As8)(Fe2As2)5 may be described as a mixture of anisotropic contributions of covalent, ionic, and metallic interatomic and inter-block interactions.