The GW-Method for Quantum Chemistry Applications: Theory and Implementation

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Density Functional Theory (DFT) relies on approximations for exchange-correlation (XC) functionals, leading to inaccuracies.
• Kohn-Sham (KS) single-particle energies and states in DFT are susceptible to these XC functional artifacts.

Purpose of the Study:

• To present the formalism and implementation of the GW method, adapted for standard quantum chemistry packages.
• To evaluate the accuracy of the GW method in correcting KS-DFT electronic structure calculations.

Main Methods:

• The study implements the GW approximation, a many-body perturbation theory method.
• Calculations were performed on a typical set of molecules to test the GW implementation.

Main Results:

• The G0W0 approximation (first iteration of GW self-consistency) significantly reduces deviations in quasi-particle energies.
• Quasi-particle energies calculated with G0W0 show an order of magnitude improvement compared to KS-DFT for ionization potentials and electron affinities.
• The G0W0 results exhibit diminished dependency on the underlying XC functional of DFT.

Conclusions:

• The GW method effectively corrects KS-DFT artifacts, leading to more accurate predictions of electronic properties.
• The G0W0 approach offers a computationally feasible way to achieve substantial accuracy improvements in electronic structure calculations.