Ab initio calculations of electronic excitations: Collapsing spectral sums

Arjan Berger (1, 2) , Lucia Reining (1, 2) , Francesco Sottile (1, 2)

1 LSI - Laboratoire des Solides Irradiés
2 ETSF - European Theoretical Spectroscopy Facility

We present a method for the evaluation of electronic excitations of advanced materials by reformulating spectral sum-over-states expressions such that only occupied states appear. All empty states are accounted for by one effective energy. Thus we keep the simplicity and precision of the sum-over-states approach while speeding up calculations by more than an order of magnitude. We demonstrate its power by applying it to the GW method, where a huge summation over empty states appears twice (screening and self-energy). The precision is shown for bulk Si and solid and atomic Ar. We then use it to determine the band gap of the technologically important oxide SnO2.

Arjan Berger, Lucia Reining, Francesco Sottile. Ab initio calculations of electronic excitations: Collapsing spectral sums. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2010, 82, pp.041103(R). ⟨10.1103/PhysRevB.82.041103⟩. ⟨hal-00562657⟩