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

Area of Science:

• Quantum Chemistry
• Computational Physics
• Many-Body Perturbation Theory

Background:

• Self-consistent field (SCF) calculations are fundamental in quantum chemistry.
• Standard methods like Møller-Plesset perturbation theory can suffer from divergences.
• Accurate prediction of electronic properties requires robust theoretical frameworks.

Purpose of the Study:

• To develop a new, regularized Fock matrix construction for SCF calculations.
• To improve the accuracy and stability of electronic structure calculations.
• To address divergence issues in perturbation theory.

Main Methods:

• Utilizing second-order perturbation theory and quasiparticle self-consistent second-order Green's function theory (GF2).
• Applying perturbative similarity renormalization group (SRG) theory for regularization.
• Introducing and optimizing three SRG-qsGF2 variants by tuning parameters.

Main Results:

• Developed three SRG-qsGF2 variants for accurate quasiparticle energy and dipole moment predictions.
• Demonstrated mitigation of divergence problems in electronic energy calculations.
• Showcased the effectiveness of the renormalized Fock matrix as an unperturbed Hamiltonian.

Conclusions:

• The proposed SRG-based Fock matrix construction offers a stable and accurate alternative for SCF calculations.
• This method enhances the reliability of quantum chemical predictions.
• The approach provides a pathway to overcome limitations of conventional perturbation theories.