Optical properties of graphite from first-principles calculations

We present theoretical results for the frequency-dependent dielectric response, both for the electric field parallel and perpendicular to the c axis of graphite. The calculations are performed using a full-potential linear muffin-tin orbital method. Our calculations show fair agreement with experimental data and the different features observed are identified from interband transitions in various regions of the Brillouin zone. The anisotropy of the dielectric function is discussed in detail and shown to be due to the difference in the optical matrix elements for the two different polarizations, which is a result of the anisotropic crystallographic and electronic properties of graphite.