Optical Properies of Graphite

A three-dimensional Fourier expansion has been developed to describe the dispersion relations E(→k) for the π bands of graphite throughout the Brillouin zone. The coefficients of the Fourier expansion are evaluated by a fit to the experimentally determined parameters of the Slonczewski-Weiss model, as well as to the optical data. Using this energy-band model, the interband contribution to the frequency-dependent dielectric constant has been calculated in the energy range 0.5<ω<6 eV for both →E⊥→c and →E∥→c. For this calculation, a numerical-integration procedure has been developed to carry out the full-zone integrations. The results for the dielectric constant are primarily dependent on the values of the McClure parameters γ₀, γ₁, γ₃, and γ₄, which enter the Slonczewski-Weiss Hamiltonian for graphite.