Universal Generalization of Density Functional Theory for Static Correlation.

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Density functional theory (DFT) faces limitations in accurately describing static correlation.
• This deficiency leads to errors in predicting molecular charges, band gaps, van der Waals forces, and reaction barriers.

Purpose of the Study:

• To develop a generalized density functional theory (DFT) that effectively incorporates static correlation.
• To create a computationally efficient method that retains DFT's speed while improving accuracy for challenging quantum molecular phenomena.

Main Methods:

• Combined one- and two-electron reduced density matrix (1- and 2-RDM) theories with DFT.
• Utilized the lowest unitary invariant of the cumulant 2-RDM to formulate a 1-RDM functional theory.
• Developed a correction for DFT functionals to address static correlation in fractional orbital occupations.

Main Results:

• Achieved a universal O(N³) generalization of DFT for static correlation.
• The method accurately captures static correlation by correcting functional convexity.
• Demonstrated predictive power by revealing the dependence of correction strength on the two-electron repulsion matrix trace.
• Successfully applied to ethylene rotation barriers, benzynes, and molecular dissociation benchmarks.

Conclusions:

• The novel theory enhances DFT's capability to treat static correlation.
• It offers a computationally efficient approach for predicting quantum molecular effects.
• Opens new avenues for accurate molecular property prediction and interpretation.