Local hybrid functionals augmented by a strong-correlation model

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Local hybrid (LH) functionals are crucial for accurate electronic structure calculations.
• Strong correlation effects pose challenges for standard density functional approximations.
• Existing methods struggle with nondynamical (NDC) and dynamical (DC) correlation descriptions.

Purpose of the Study:

• To adapt and apply the KP16/B13 strong-correlation factor to local hybrid functionals.
• To investigate methods for deriving a position-dependent strong-correlation factor qAC(r).
• To evaluate the performance of these modified LH functionals in addressing correlation deficiencies.

Main Methods:

• Modification of LH functionals by incorporating a KP16/B13-style strong-correlation factor.
• Derivation of the factor qAC(r) using a local adiabatic connection approach.
• Evaluation of different NDC expressions, including a modified B13 NDC term with Patra's exchange-hole curvature.
• Self-consistent implementation within a developer's version of the Turbomole program.

Main Results:

• Hybrid approaches for deriving the strong-correlation factor yield significant improvements over direct derivation.
• A modified B13 NDC expression shows promising results, reducing fractional-spin errors and bond dissociation curve deficiencies.
• The modified LH functional maintains high accuracy for atomization energies and reaction barriers in weakly correlated systems.
• Performance analysis identifies areas for further refinement of strong-correlation corrected LHs.

Conclusions:

• Adapting the KP16/B13 strong-correlation factor via hybrid methods offers a promising route to enhance LH functionals.
• These improved functionals effectively address deficiencies in describing strongly correlated systems.
• The study provides a foundation for developing more robust and accurate quantum chemical methods.