Optical spectra of alkali-metal fluorides

We have studied the virtue of different approximations for quasiparticle energies in the calculation of optical spectra including excitonic effects by solving the Bethe-Salpeter equation (BSE). To this end we have computed exemplarily optical spectra of the three alkali-metal fluorides LiF, NaF, and KF using quasiparticle energies resulting from two different approximations of the self-energy operator in Hedin's $GW$ approach as well as electronic energies and wave functions obtained by employing self-interaction corrected pseudopotentials. Additionally, two simple further approximations for quasiparticle energies that use input either from experiment or from preceding quasiparticle calculations for a small set of wave vectors are included in this investigation.