First-principles studies on electronic structures of superatomic compounds [Co6Se8(PMe3)6][C60] in several cubic structures

Abstract

Structural features, electronic structures, and optical properties of superatomic compounds [Co6Se8(PMe3)6][C60] with rock-salt, cesium chloride, and zinc-blende structures were investigated from first principles. Partial electronic density of states, highest occupied molecular orbital, and lowest unoccupied molecular orbital were given and used to discuss the detailed electronic structures. Dielectric function, refractive index, reflectivity, absorption coefficient, and energy loss functions under several pressures were calculated and used to investigate the optical properties. We found that Co6Se8(PMe3)6 transfers electrons and C60 receives electrons, making contributions to electron communications between the positive and negative counterparts on the basis of electrostatic interactions. The superatomic structures are made from assemblies of charge-rich and charge-poor molecular precursors. In the solid state, charge is transferred between the components, with a net reduction of C60 by less than one electron (0.75 electron approximately).