Smart local orbitals for efficient calculations within density functional theory and beyond.

Area of Science:

• Computational Physics
• Materials Science
• Quantum Chemistry

Background:

• Localized basis sets in projector augmented wave (PAW) formalism offer computational efficiency in density functional theory (DFT).
• High accuracy in DFT calculations often necessitates extensive basis sets, complicating result interpretation.
• A need exists for more interpretable and efficient basis sets in electronic structure calculations.

Purpose of the Study:

• To develop a method for reducing the size of localized basis sets in DFT calculations.
• To improve the interpretability of DFT results without sacrificing accuracy.
• To enable efficient post-processing of electronic structure calculations.

Main Methods:

• Subdiagonalization of atomic blocks of the Hamiltonian to obtain local orbitals (LOs).
• Identification of a relevant subset of LOs that accurately describe physics near the Fermi level.
• Demonstration of near block-diagonality in the LO basis.

Main Results:

• A reduced, accurate basis set of local orbitals is obtained.
• The Hamiltonian in the LO basis is shown to be nearly block-diagonal.
• The method allows for efficient post-processing, including electron transport analysis and tight-binding Hamiltonian extraction.

Conclusions:

• The presented method effectively reduces basis set redundancy in DFT calculations.
• Accurate physical descriptions, especially around the Fermi level, are maintained with the reduced basis set.
• This approach facilitates efficient and accurate post-processing of DFT results for materials simulations.