Accurate prediction of quasi-particle energies is critical to investigate novel materials. However, the performance of commonly used G0W0 approach and its particle-particle counterpart G0T0 approach have undesired dependence on the choice of the density functional approximations (DFAs). To eliminate the starting point dependence, we apply the renormalized singles (RS) Green's function in the one-shot GW and T-Matrix approaches, denoted as GRSWRS and GRSTRS. The recently developed RS Green's function incorporates the effect of all single excitation contributions by combining the form of HF self-energy with DFA orbitals. In GRSWRS and GRSTRS, the RS Green's function is used as a new starting point and is used to calculate the effective interaction. We show that GRSWRS and GRSTRS combining with different DFAs provide excellent prediction for ionized potentials and core level binding energies. For core state calculations, GRSWRS and GRSTRS reproduce the correct spectral function with the desired peak by using RS Green's function in the random phase approximation (RPA) calculation. We demonstrate that using RS Green's function can provide systematical improvement on the accuracy and significant elimination of the starting point dependence.

Renormalized singles Green’s function in GW and T-matrix approximation for accurate quasi-particle energies

ACS Fall 2021

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