Role of exact exchange in thermally-assisted-occupation density functional theory: A proposal of new hybrid schemes

TL;DR

This paper introduces hybrid schemes that incorporate exact exchange into thermally-assisted-occupation density functional theory (TAO-DFT), enhancing the description of nonlocal exchange effects and improving performance for systems with strong static correlation.

Contribution

The authors develop new hybrid functionals combining exact exchange with TAO-DFT, demonstrating improved accuracy for strongly correlated systems and noncovalent interactions.

Findings

Hybrid TAO-DFT functionals perform well for static correlation effects.

Hybrid functionals improve thermochemistry and reaction energy predictions.

Inclusion of dispersion corrections enhances noncovalent interaction descriptions.

Abstract

We propose hybrid schemes incorporating exact exchange into thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] for an improved description of nonlocal exchange effects. With a few simple modifications, global and range-separated hybrid functionals in Kohn-Sham density functional theory (KS-DFT) can be combined seamlessly with TAO-DFT. In comparison with global hybrid functionals in KS-DFT, the resulting global hybrid functionals in TAO-DFT yield promising performance for systems with strong static correlation effects (e.g., the dissociation of H2 and N2, twisted ethylene, and electronic properties of linear acenes), while maintaining similar performance for systems without strong static correlation effects. Besides, a reasonably accurate description of noncovalent interactions can be efficiently achieved through the inclusion of dispersion corrections in hybrid TAO-DFT. Relative to semilocal density functionals in TAO-DFT, global hybrid functionals in TAO-DFT are generally superior in performance for a wide range of applications, such as thermochemistry, kinetics, reaction energies, and optimized geometries.