A calculation of the electronic band structure of KC *

Abstract

Results of an ab initio band structure calculation for first stage potassium-graphite, KC 8, are presented along several high symmetry directions in the Brillouin zone. In the first step, we find the KKR band structure using the muffin tin approximation. In the second step we introduce the corrections to the muffin tin potential, leading to the final bands. Our band structure, excludingthe bands originating from the 3p and 4s levels of potassium, is in good agreement with the predictions of the folded band model of two dimensional graphite. The bottom of the K 4s band lies about 1.5 eV above the Fermi level. Preliminary indications are that our Fermi surface will lack the central, isotropic pocket of carriers predicted earlier, and will be more in agreement with the folded bands. We have also studied the lowest energy critical point transitions and find a series of saddle point transitions centered at 4.1 eV, roughly consistent with the experimental low energy electron loss spectra.