Electrostatic interactions and staging in graphite intercalation compounds

The nonlinear Thomas-Fermi equations which describe the screening of intercalant layers in graphite intercalation compounds are solved analytically in the approximation that the graphite $c$-axis band dispersion is neglected. The total energy of the system of charged intercalant layers and the self-consistent charge distribution are calculated analytically for general configurations of the intercalant layers. Because of electrostatic screening, pure stage configurations minimize the total (electrostatic plus band) energy for fixed chemical potential. Estimates of the stage dependence of both the electrostatic and elastic interactions between intercalant layers are presented. Experimental tests of these mechanisms for staging are suggested.