Precision benchmarks for solids: G0W0 calculations with different basis sets

The approximation within many-body perturbation theory is the state of the art for computing quasiparticle energies in solids. Typically, Kohn–Sham (KS) eigenvalues and eigenfunctions, obtained from a Density Functional Theory (DFT) calculation are used as a starting point to build the Green’s function and the screened Coulomb interaction , yielding the one-shot self-energy if no further update of these quantities are made. Multiple implementations exist for both the DFT and the subsequent calculation, leading to possible differences in quasiparticle energies. In the present work, the quasiparticle energies for states close to the band gap are calculated for six crystalline solids, using four different codes: Abinit, exciting, FHI-aims, and GPAW. This comparison helps to assess the impact of basis-set types (planewaves versus localized orbitals) and the treatment of core and valence electrons (all-electron full potentials versus pseudopotentials). The impact of unoccupied states as well as the algorithms for solving the quasiparticle equation are also briefly discussed. For the KS-DFT band gaps, we observe good agreement between all codes, with differences not exceeding 0.1 eV, while the results deviate on the order of 0.1-0.3 eV. Between all-electron codes (FHI-aims and exciting), the agreement is better than 15 meV for KS-DFT and, with one exception, about 0.1 eV for band gaps.     «

The approximation within many-body perturbation theory is the state of the art for computing quasiparticle energies in solids. Typically, Kohn–Sham (KS) eigenvalues and eigenfunctions, obtained from a Density Functional Theory (DFT) calculation are used as a starting point to build the Green’s function and the screened Coulomb interaction , yielding the one-shot self-energy if no further update of these quantities are made. Multiple implementations exist for both the DFT and the subsequent calcu...     »