Absorption coefficient calculated from the Bethe-Salpeter equation for (solid lines) plotted alongside the experimental results at (circles) (Ref. 1) for perpendicular (black curves on the left) and parallel (red curves on the right) light polarization. Lorentzian broadening of 0.001 eV has been added to the calculated results to simulate the lifetime and instrumental broadening inherent to the experiment. The broadening artifacts below the absorption edge have been subtracted.Reuse & Permissions