GW with hybrid functionals for large molecular systems.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Stochastic methods are increasingly used for large-scale electronic structure calculations.
• Time-dependent Hartree-Fock (TDHF) and Density Functional Theory (DFT) are common starting points for electronic structure methods.
• Calculating quasiparticle energies accurately is crucial for understanding material properties.

Purpose of the Study:

• To develop a low-cost method for stochastic sampling of static exchange in TDHF-type propagation.
• To enable the use of hybrid DFT as a starting point for stochastic GW calculations.
• To improve the efficiency and accuracy of quasiparticle energy predictions.

Main Methods:

• Stochastic sampling of static exchange during time-dependent propagation.
• Utilizing Generalized Kohn-Sham (GKS) orbitals and energies for Green function construction.
• Employing an optimally tuned hybrid DFT functional as the starting point.

Main Results:

• Successfully implemented a low-cost stochastic approach for static exchange.
• Demonstrated the effectiveness of hybrid DFT starting points for stochastic GW.
• Showcased that GKS orbitals/energies improve Green function and Coulomb interaction building.
• Reduced starting point dependency in one-shot stochastic GW calculations.

Conclusions:

• The presented method offers an efficient and accurate route to quasiparticle energies.
• Optimally tuned hybrid DFT starting points significantly enhance one-shot stochastic GW.
• This approach bypasses the need for computationally expensive self-consistent GW iterations.