Ab initio calculation of excitonic effects in the optical spectra of   semiconductors
  An ab initio approach to the calculation of excitonic effects in the optical absorption spectra of semiconductors and insulators is formulated. It starts from a quasiparticle bandstructure calculation and is based on the relevant Bethe--Salpeter equation.   An application to bulk silicon shows a substantial improvement with respect to previous calculations in the description of the experimental spectrum, for both peak positions and lineshape. 
Stefan Albrecht (1) Lucia Reining (1) Rodolfo Del Sole (2) Giovanni   Onida (2)