Discrete-variational Xα calculations of graphite and alkali-metal graphite intercalation compounds

摘要

First-principles molecular orbital calculationsusing discrete-variational (DV)-Xα method are carried out on themodel clusters of graphite and alkali-metal graphite intercalationcompounds MCx(M = Li, Na, K, Rb, and Cs). Results of thecalculations are used so as to simulate the experimentally observednear-edge X-ray-absorption fine-structures (XANES) andultraviolet photoelectron spectra. For the clusters of graphite andKCx, the calculated partial electronic densities of states (PDOSs)are in good agreement with the experimental C K-edge and K K-edge XANES spectra, respectively. Furthermore, the accordancebetween the calculated DOSs and the observed UPS spectra ofgraphite and RbCx is also satisfactory. It is shown that the Fermilevel is pushed up into the conduction band of graphite by dopingalkali metals.