Electronic excitations of LiI within many-body perturbation theory

We report the calculated quasiparticle band structure and optical absorption spectrum of LiI, using many-body perturbation theory. Density-functional theory within local density approximation is used to calculate the ground-state properties of the system. The quasiparticle band structure is evaluated within the GW approximation. Taking the electron-hole interaction into account, electron-hole pair states and optical excitations are derived from the solution of the Bethe-Salpeter equation for the electron-hole two-particle Green function. The band gap is estimated within the GW approximation as 6.3 eV, which is in good agreement with the experimental result of 6.4 eV. And the calculated optical spectrum is also in agreement with experimental data.