抄録
The electronic states of the stage-2 hydrogen-potassium-graphite ternary intercalation compounds C8KHx (x=0.5, 1.0) are investigated. The band structures of these compounds are determined in a local density functional formalism using the self-consistent numerical-basis-set LCAO (linear combination of atomic orbitals) method. We estimate the amount of the charge transfer among the individual atoms and show that the hydrogen atom acts as an acceptor to graphite, while the potassium atom acts as a donor. The charge transfer to the hydrogen atoms is imperfect and therefore the hydrogen 1s state forms a partially occupied metallic band. This hydrogen-1s-like band coexists with the graphite-π*-like bands at the Fermi level. These results indicate that C8KHx has a feature of the metallic hydrogen. Our results are consistent with recent experimental results of electrical conductivity, thermoelectric power, ESR and NMR.
