Halogen and Chalcogen Binding Dominated by Density-Driven Errors.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Density Functional Theory (DFT) commonly uses dispersion corrections to improve energetics of noncovalent interactions.
• However, density-driven errors in uncorrected DFT can sometimes exceed dispersion corrections for specific molecular systems.

Purpose of the Study:

• To investigate the impact of dispersion corrections on DFT energetics, particularly for systems with sigma-hole interactions.
• To evaluate the effectiveness of Hartree-Fock densities (HF-DFT) as an alternative for improving energetics in abnormal cases.

Main Methods:

• Comparison of DFT energetics with and without dispersion corrections.
• Evaluation of HF-DFT (using Hartree-Fock densities) for specific molecular interactions.
• Analysis of results for systems with sigma-hole interactions, halides, and standard benchmarks like pnictogen bonds and the S22 dataset.

Main Results:

• Dispersion corrections can worsen bond energies in cases with large density-driven DFT errors, such as certain molecules and halides with sigma-hole interactions.
• HF-DFT significantly improves bond energies in these abnormal situations, outperforming standard dispersion corrections.
• Pnictogen bonds and the S22 dataset, considered normal cases, do not benefit from HF-DFT.

Conclusions:

• The parametrization of dispersion interactions must account for these abnormal situations where standard corrections fail or degrade results.
• HF-DFT offers a viable alternative for improving energetics in specific cases dominated by density-driven errors.