Renormalized Singles Green's Function in the T-Matrix Approximation for Accurate Quasiparticle Energy Calculation

Abstract

We combine the renormalized singles (RS) Green's function with the T-Matrix approximation for the single-particle Green's function to compute quasiparticle energies for valence and core states of molecular systems. The G RS T 0 method uses the RS Green's function that incorporates singles contributions as the initial Green's function. The G RS T RS method further calculates the generalized effective interaction with the RS Green's function by using RS eigenvalues in the T-Matrix calculation through the particle-particle random phase approximation. The G RS T RS method provides significant improvements over the one-shot T-Matrix method G 0 T 0 as demonstrated in calculations for GW100 and CORE65 test sets. It also systematically eliminates the dependence of G 0 T 0 on the choice of density functional approximations (DFAs). For valence states, the G RS T RS method provides an excellent accuracy, which is better than G 0 T 0 with Hartree-Fock (HF) or other DFAs. For core states, the G RS T RS method correctly identifies desired peaks in the spectral function and significantly outperforms G 0 T 0 on core level binding energies (CLBEs) and relative CLBEs, with any commonly used DFAs.