Simple approximate physical orbitals for GW quasiparticle calculations.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Calculating quasiparticle energies using GW methods requires unoccupied orbitals from density functional theory (DFT).
• Generating these unoccupied orbitals becomes computationally prohibitive for large and complex systems.

Purpose of the Study:

• To develop a computationally efficient method for quasiparticle energy calculations in large systems.
• To replace the need for a full set of unoccupied DFT orbitals with accurate approximations.

Main Methods:

• The study proposes using a combination of plane waves and localized basis DFT orbitals to construct approximate physical orbitals.
• These approximate orbitals represent the continuum and resonant states of the system.
• The method involves using only a minimal number of unoccupied DFT orbitals.

Main Results:

• The proposed approach achieves accurate quasiparticle energy calculations without sacrificing precision.
• It significantly reduces the computational cost associated with generating unoccupied orbitals.
• An order of magnitude speedup in calculations for large systems is demonstrated.

Conclusions:

• This novel method offers a computationally feasible pathway for accurate electronic structure calculations in large systems.
• It overcomes the bottleneck of generating unoccupied orbitals in standard GW calculations.
• The approach paves the way for more extensive studies of large-scale materials and molecules.