Perspective: Kohn-Sham density functional theory descending a staircase.

Area of Science:

• Chemical Physics
• Computational Chemistry
• Quantum Mechanics

Background:

• Kohn-Sham density functional theory (KS-DFT) is a widely used method for electronic structure calculations.
• Applications span both molecular and solid-state systems.
• Ongoing research addresses limitations and expands KS-DFT's applicability.

Purpose of the Study:

• To provide a perspective on current challenges and advancements in KS-DFT.
• To discuss the treatment of specific system types and interactions.
• To review the development and ingredients of exchange-correlation functionals.

Main Methods:

• Review of theoretical developments and computational approaches in KS-DFT.
• Analysis of the treatment of open-shell and multiconfigurational systems.
• Examination of noncovalent interactions and functional development strategies.
• Discussion of exchange-correlation functional ingredients and time-dependent extensions.

Main Results:

• Progress in treating strongly correlated and multireference systems using broken-symmetry determinants.
• Improved descriptions of noncovalent interactions.
• Successful development of new functionals (e.g., MN15-L, MN15) through optimization against diverse databases.
• Advancements in time-dependent density functional theory (TD-DFT) for excited states.

Conclusions:

• KS-DFT is a rapidly evolving field with significant progress in addressing complex chemical and physical problems.
• The development of more accurate and universal functionals remains a key objective.
• Continued research is crucial for expanding the predictive power of KS-DFT in electronic structure calculations.