Exact exchange and Wilson-Levy correlation: a pragmatic device for studying complex weakly-bonded systems

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of interaction energies in weakly bonded systems is crucial for understanding molecular interactions.
• Existing density-functional theory (DFT) methods sometimes struggle with intermediate-range interactions.

Purpose of the Study:

• To evaluate the performance of the Wilson-Levy (WL) correlation functional combined with Hartree-Fock (HF) theory for weakly bonded systems.
• To compare the HF+WL approach against popular and newly developed DFT functionals.

Main Methods:

• Utilized the Hartree-Fock (HF) method in conjunction with the Wilson-Levy (WL) correlation functional.
• Calculated interaction energies for rare-gas dimers, methane dimer isomers, benzene dimer, naphthalene dimer, and various base-pair dimers (pyrimidine, cytosine, uracil, guanine).
• Compared results with B3LYP, PBE, X3LYP, and xPBE functionals, and discussed in the context of exact-exchange (EXX) DFT.

Main Results:

• The HF+WL approach successfully reproduced the binding trends observed across all investigated weakly bonded systems.
• HF+WL demonstrated good performance for rare-gas dimers, methane dimer isomers, and aromatic/nucleobase dimers.
• The study provides a basis for a potential new EXXWL exchange-correlation functional.

Conclusions:

• The HF+WL method is a reliable approach for studying interaction energies in weakly bonded molecular systems.
• HF+WL offers a competitive alternative to current DFT functionals for these types of calculations.
• Further development of an EXXWL functional is suggested based on these findings.