Maximum locality in occupied and virtual orbital spaces using a least-change strategy

Area of Science:

• Quantum Chemistry
• Computational Physics

Background:

• Hartree-Fock (HF) theory is a fundamental method in quantum chemistry.
• Obtaining localized orbitals is crucial for interpreting electronic structure.
• Standard localization schemes often struggle with virtual orbital spaces.

Purpose of the Study:

• Introduce a novel strategy for localized orthonormal Hartree-Fock orbitals.
• Develop a method that localizes both occupied and virtual orbital spaces effectively.
• Improve the interpretability of HF wavefunctions through enhanced orbital localization.

Main Methods:

• Minimizing the transformation matrix size from atomic to HF orbital basis.
• Applying a new strategy to achieve localized occupied and virtual orbital spaces.
• Comparing the locality of the new virtual orbitals with standard methods and Löwdin orthonormalization.

Main Results:

• The new strategy successfully generates localized occupied and virtual orbital spaces.
• Occupied orbital localization is comparable to existing standard schemes.
• Virtual orbital localization achieves similarity to Löwdin orthonormalization, outperforming standard schemes.
• The method optimizes the orthonormal basis without significant delocalization.

Conclusions:

• The proposed strategy offers an effective approach for obtaining localized orthonormal HF orbitals.
• This method overcomes limitations of standard schemes in localizing virtual orbitals.
• The enhanced localization improves the basis set optimization without compromising delocalization, aiding electronic structure analysis.