) refers to the Coulomb potential. The popular GW approximation is obtained by setting δΣ δV (3) = 0. These equations may either be solved directly in the spectral domain, resulting in the spectral method or, for instance, by making use of the residue theorem in the form of contour deformation techniques (CD). Furthermore, these equations can be solved by performing only a single GW iteration, resulting in the single shot G 0 W 0 method or by employing the eigenvalue-only self-consistent GW approach, often abbreviated as evGW. Upon the calculation of the self-energy, quasiparticle energies can be obtained by improving the KS energies in first order, replacing the energy contribution of the XC functional with the self-energy operator.