How well can density functional methods describe hydrogen bonds to pi acceptors?

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Investigated five pi hydrogen bonding systems using Density Functional Theory (DFT).
• Included systems like H2O-benzene, ammonia-benzene, and HCl-benzene.
• Utilized newly developed DFT methods for accurate calculations.

Discussion:

• Compared the performance of MPW1B95, MPWB1K, PW6B95, and PWB6K against B3LYP and PW91.
• Validated HCl-benzene calculations with coupled cluster theory, supporting experimental data.
• Evaluated energetic and geometrical predictions for pi hydrogen bonding.

Key Insights:

• MPW1B95, MPWB1K, PW6B95, and PWB6K demonstrate high accuracy for pi hydrogen bonding.
• B3LYP showed deficiencies, while PW91 was less accurate in these systems.
• Newer DFT methods provide reliable predictions for non-covalent interactions.

Outlook:

• Recommend PWB6K for studying larger pi hydrogen bonded systems.
• Applications include molecular recognition, protein folding, and crystal packing.
• Future research can leverage these accurate DFT methods for complex biological and material systems.