Analyzing density-driven errors: Principles and pitfalls

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Density-corrected density functional theory (DC-DFT) decomposes errors in density functional theory (DFT) calculations.
• Hartree-Fock (HF) densities are often used in practical DC-DFT (HF-DFT) to reduce energetic errors.
• Accurate density approximations are crucial for reliable DC-DFT analyses.

Purpose of the Study:

• To identify and illustrate common pitfalls in analyzing errors within the HF-DFT framework.
• To critically evaluate the accuracy of density error interpolators and proxy densities used in DC-DFT.
• To investigate the reasons behind the consistent performance of HF-DFT for chemical barrier heights.

Main Methods:

• Application of DC-DFT principles to analyze HF-DFT errors.
• Calculation of exact density-driven errors for one- and two-electron systems.
• Analysis of existing benchmarking data for proxy densities used in DC-DFT.

Main Results:

• Identified chronic inaccuracies in common interpolators for density-driven errors.
• Demonstrated that proxy benchmark densities are often too inaccurate for reliable DC-DFT.
• Showcased ideal density-driven errors for simple model systems.

Conclusions:

• The success of HF-DFT for barrier heights may not solely depend on error cancellation.
• Common methods for assessing density errors in DC-DFT can be misleading.
• Further research is needed to understand the consistent improvements observed with HF-DFT.