Theoretical optical properties of highly birefringent compounds

In this work, the layered compound orpiment (As₂S₃), elemental boron and orthorhombic sulfur, polytetrafluoroethylene (PTFE) and ammonium nitrate are examined regarding their optical properties and extremely large birefringence effects. A comparison of observed and theoretical optical properties will be made. The theoretical results are obtained using the Bethe-Salpeter equation to treat the equation of motion of the excited electron-hole pair. This work can serve as a test of the peculiar optical properties and the ability to predict them from first principles.