Nuclear magnetic resonance in higher-stage graphite intercalation compounds.

Abstract

The theoretical results of $^{13}\mathrm{C}$ nuclear magnetic resonance shifts of higher-stage graphite intercalation compounds (GIC's) are presented. In this calculation a new formalism for calculating the chemical shifts and Knight shifts for a metallic energy-band system is proposed. In this formalism the overall feature of graphite \ensuremath{\pi} bands and \ensuremath{\sigma} bands which are mixed due to the inhomogeneous c-axis charge distribution is taken into account. The calculated results show several resonant lines with different values of scalar and dipolar Knight shifts which can be assigned to the inequivalent carbon atoms due to A-B stacking and inhomogeneous c-axis charge distribution of the graphite layers. The theoretical results of the NMR shifts on the basis of the first-principles band calculations of the higher-stage GIC's are in good agreement with the observed ones.