Electronic Structure of Potassium-Graphite Intercalation Compound: C₈K

The electronic band structure of the first-stage potassium-graphite intercalation compound C 8 K was calculated by a semi-empirical tight-binding scheme. The calculated Fermi surfaces can be classified into two distinct types. One is potassium-like and nearly isotropic; the other is carbon-like and of cylindrical shape. In addition, the cylindrical portions show nesting property, which is likely to induce charge-density-wave instability. The isotropic portions of the Fermi surfaces are responsible for the large reduction of anisotropy in conductivity of C 8 K relative to graphite. The calculated density of states has a peak around the Fermi level and is in good agreement with the observed density of states derived from the specific heat measurements.