The Importance of Being Inconsistent.

Area of Science:

• Computational chemistry
• Quantum mechanics
• Materials science

Background:

• Density functional theory (DFT) is a powerful quantum mechanical method for electronic structure calculations.
• Approximations in DFT functionals often lead to errors, such as self-interaction and delocalization errors.
• Understanding the role of self-consistency is key to improving DFT accuracy.

Purpose of the Study:

• To review the significance of self-consistency in various DFT formulations.
• To analyze the sources of errors in DFT calculations, distinguishing between functional and density errors.
• To provide insights into reducing common DFT errors like self-interaction and delocalization.

Main Methods:

• Application of a recent analysis framework to Kohn-Sham DFT, orbital-free DFT, and partitioned DFT.
• Distinguishing between errors originating from approximate exchange-correlation functionals and those from the self-consistent electronic density.
• Reviewing historical developments and applications of self-consistency analysis in DFT.

Main Results:

• The analysis successfully differentiates errors in functionals from errors in the self-consistent density across different DFT approaches.
• Errors in DFT calculations, particularly self-interaction and delocalization errors, can often be substantially mitigated by employing improved self-consistent densities.
• The study highlights the critical role of the electronic density's quality in DFT accuracy.

Conclusions:

• Self-consistency plays a vital role in the accuracy of DFT calculations.
• Improving the self-consistent density offers a promising avenue for reducing systematic errors in DFT.
• The presented analysis provides a valuable tool for diagnosing and addressing errors in electronic structure computations.