Electronic structure of graphite: Effect of hydrostatic pressure

We present theoretical results for the electronic structure of graphite using a full-potential linear muffin-tin-orbital method. The calculations are performed at ambient pressure and at hydrostatic pressures of 5 and 10 GPa. Our ambient pressure results are in agreement with recent independent calculations as well as with photoemission experimental data. Our calculations at 5 and 10 GPa show a splitting of the σ bands indicating an increase in the overlap between wave functions centered on different carbon atoms. The calculated pressure dependence of the ${\mathit{A}}_1$ and ${\mathit{A}}_2$ transitions (attributed to transitions occurring at the symmetry point K) is in agreement with recent optical reflectivity data. Also, the compressibility is calculated to be highly anisotropic, in excellent agreement with experimental data.