Levels of self-consistency in the GW approximation

Area of Science:

• Quantum chemistry
• Computational condensed matter physics

Background:

• The GW approximation is crucial for accurate electronic structure calculations.
• Achieving full self-consistency in GW calculations is computationally demanding.
• Understanding the impact of self-consistency levels is key for efficient methods.

Purpose of the Study:

• To investigate the effects of self-consistency on GW calculations for atoms and molecules.
• To introduce and validate a novel partially self-consistent GW (scGW) scheme.
• To compare the accuracy and efficiency of scGW against standard GW methods.

Main Methods:

• Performed GW calculations at various self-consistency levels.
• Developed a partially self-consistent GW approach by fixing the correlation part of the self-energy.
• Compared results with fully self-consistent GW, GW(0), and G(0)W(0) approximations.

Main Results:

• Partially scGW shows excellent agreement with fully scGW for total energies and ionization potentials.
• The scGW method significantly reduces computational cost compared to full self-consistency.
• scGW and self-consistent GW yield comparable ionization energies to G(0)W(0), but superior total energies.

Conclusions:

• The partially self-consistent GW scheme offers a computationally efficient yet accurate alternative.
• This method provides a good balance between accuracy and computational expense for electronic structure studies.
• The findings enable more feasible high-throughput calculations in materials science and chemistry.