Pair-Density Functional Theory Based on Spin-Projected Unrestricted Hartree-Fock Method: A Density-Corrected Version.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Accurate and efficient treatment of electron correlation is crucial in quantum chemistry.
• Existing methods like spin-projected unrestricted Hartree-Fock with pair-density functional theory (SU-PDFT) offer cost-effectiveness but have accuracy limitations.

Purpose of the Study:

• To introduce a density-corrected version of SU-PDFT (DC-SU-PDFT).
• To enhance the accuracy of SU-PDFT for challenging quantum chemical calculations.
• To provide a computationally efficient alternative to multiconfiguration pair-density functional theory (MC-PDFT).

Main Methods:

• Development of the density-corrected SU-PDFT (DC-SU-PDFT) method.
• Incorporation of a density functional theory contribution into the self-consistent step.
• Utilizing spin-projected unrestricted Hartree-Fock (SUHF) with an on-top pair-density functional.

Main Results:

• DC-SU-PDFT significantly improves upon SU-PDFT for spin splittings and bond dissociation energies.
• The method shows enhanced accuracy for isomerization energies of diatomic molecules.
• Achieved accuracy comparable to MC-PDFT while maintaining favorable computational cost.

Conclusions:

• DC-SU-PDFT offers a superior balance of accuracy and computational efficiency.
• The method provides a promising avenue for treating static and dynamic electron correlation.
• This advancement addresses a central challenge in quantum chemistry.