In this work we compare the optical absorption of extended systems calculated starting from the density-density and current-current linear response formalisms within the equilibrium many-body perturbation theory(MBPT). We show how, using the latter, one can incur in errors due to quasiparticle lifetimes, electron-hole interaction or the presence of a Drude tail. These errors are found in different papers and computational codes. We present a solution for each one of these problems.
Poster: Excitons, lifetime and Drude tail within the current-current response framework
Paper: Optical properties of periodic systems within the current-current response framework: pitfalls and remedies