The SternheimerGW code evaluates the quasi-particle correction to the DFT results in the GW approximation. The Greens function G and the screened Coulomb W interaction are evaluated solving Sternheimer equations (linear response problem) instead of summing over the virtual, unoccupied subspace.
The main target of SternheimerGW are very accurate calculations for crystals and surfaces. We can evaluate the full band structure along any user selected k-point path. In addition to the quasi-particle corrections to the eigenvalues, we provide the full frequency dependent spectral function, which can be compared to angular-resolved photo-emission spectroscopy (ARPES) experiments.