Measuring Density-Driven Errors Using Kohn-Sham Inversion.

Area of Science:

• Computational chemistry
• Quantum mechanics
• Density functional theory

Background:

• Kohn-Sham (KS) inversion, determining the exact KS potential from a given electron density, is computationally challenging, especially within localized basis sets.
• Accurate KS potentials are crucial for the predictive power of density functional theory (DFT).

Purpose of the Study:

• To evaluate the precision and reliability of various KS inversion schemes.
• To quantify density-driven errors in KS inversion.
• To assess the accuracy of Hartree-Fock density functional theory (HF-DFT) as a practical alternative.

Main Methods:

• Investigated multiple KS inversion techniques.
• Estimated density-driven errors.
• Compared HF-DFT accuracy against DFT results using coupled-cluster singles, doubles, and triples (CCSD(T)) densities.
• Examined two specific molecular systems: stretched NaCl and the HO·Cl^- radical.

Main Results:

• Developed methods to estimate density-driven errors with useful accuracy.
• Demonstrated that HF-DFT achieves accuracy comparable to standard DFT when significant density-driven errors are present.
• Showed that a simple HF-DFT approximation substantially reduces errors.
• Validated findings using stretched NaCl and HO·Cl^- radical examples.

Conclusions:

• KS inversion poses significant challenges in localized basis sets.
• HF-DFT presents a reliable and accurate method for electronic structure calculations, particularly when density-driven errors are substantial.
• The findings support the practical utility of HF-DFT for accurate quantum chemical computations.