Renormalized Singles Green’s Function for Quasi-Particle Calculations beyond the G0W0 Approximation

Quasi-particle energies and band gaps in particular are critical for investigating novel materials. Commonly used density functional approximations (DFAs) systematically underestimate band gaps, and GW approximation is the established method of choice for good accuracy and reliability. However, G0W0 has some undesired dependence on the DFA, while self-consistent GW (scGW) is expensive and not consistent in accuracy improvement. Here a simple and efficient GRSW0 approach has been developed: a subspace diagonalization of the Hartree–Fock (HF) Hamiltonian with the DFA density matrix provides the new reference Green’s function GRS that incorporates the effect of all single excitation contributions to the self-energy, thereby essentially eliminating the starting-point dependence. Calculations for molecules and large band gap solids demonstrate the significant improvement over G0W0 and greatly reduced dependence on the initial DFA. GRSW0 approach also improve results for other bulks over G0W0, but to a lesser e...