DENSITY OF STATES, CHARGE TRANSFER, AND OPTICAL PROPERTIES OF MAGNESIUM DIBORIDE

Abstract

We performed ab-initio, local density functional calculations of the electronic structure, charge transfer, and optical properties of MgB2, using the LCAO formalism. The Fermi level of MgB 2 cuts through relatively narrow electron bands which have a dominant contribution from B (2p) states. There is a substantial charge transfer from magnesium to boron atoms. We found the ionic formula for this material to be [Formula: see text]. A clearly metallic distribution of the electronic charge density in the plane of boron atoms is interwoven with a visibly covalent one in the direction perpendicular to this plane. The calculated optical conductivities from the direct inter-band transitions exhibit a strong anisotropy between σxx(ω) or σyy(ω) and σzz(ω). Due to our application of the BZW procedure, major peaks in the density of states above the Fermi level are at markedly higher energies (1–1.5 eV) than the results of previously reported ones. A similar pattern is followed by our findings for optical conductivities.