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

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 one-shot methods G(0)T(0) and G(0)W(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. For valence states, the G(RS)T(RS) method provides excellent accuracy, which is better than that of G(0)T(0) and G(0)W(0). For core states, the GRSTRS method identifies correct peaks in the spectral function and significantly outperforms G(0)T(0) on core-level binding energies (CLBEs) and relative CLBEs.

Automated summary

This study introduces the G(RS)T(0) and G(RS)T(RS) methods, which combine the RS Green's function and T-matrix approximation to compute quasiparticle energies in molecular systems, comparing their performance with G(0)T(0) and G(0)W(0) methods for valence and core states, as well as the dependence of G(0)T(0) method on density functional approximations.