Renormalization group approach to second-order Green's function theory

TL;DR

This paper presents a novel renormalization approach for second-order Green's function theory, improving the accuracy and stability of electronic structure calculations by integrating perturbative SRG techniques.

Contribution

It introduces a new SRG-based regularization scheme for second-order Green's function theory, enhancing quasiparticle energy predictions and addressing divergence issues in perturbation methods.

Findings

Accurate quasiparticle energies and dipole moments achieved.

Mitigation of divergence problems in perturbation theory.

Introduction of three optimized SRG-qsGF2 variants.

Abstract

In this work, we introduce a new approach for constructing a renormalized and regularized Fock matrix for self-consistent field calculations. The scheme relies on second-order perturbation theory and is conceptually related to quasiparticle self-consistent second-order Green's function theory (GF2). The regularization is derived within the framework of perturbative similarity renormalization group (SRG) theory. By optimizing both the regularization and spin-scaling parameters, we introduce three SRG-qsGF2 variants that enable accurate predictions of quasiparticle energies and dipole moments. Lastly, we demonstrate that formulating second-order perturbation theory for the total electronic energy using the renormalized SRG-qsGF2 Fock matrix as the unperturbed Hamiltonian mitigates divergence problems commonly observed in conventional M{\o}ller--Plesset perturbation theory.