Potential energy barrier for proton transfer in compressed benzoic acid

Area of Science:

• Physical Chemistry
• Materials Science
• Solid-State Physics

Background:

• Benzoic acid (BA) serves as a key model for investigating proton transfer (PT) reactions.
• Solid-state properties of BA under high pressure are of significant interest for tuning PT barriers.

Purpose of the Study:

• To evaluate the proton transfer barrier in solid benzoic acid across a pressure range of 1 atm to 15 GPa.
• To understand the influence of pressure on hydrogen bond symmetrization in BA.

Main Methods:

• Computational simulations were employed to model benzoic acid under varying pressures.
• Analysis focused on O⋯O contact distances within BA dimers and their relation to the PT barrier.

Main Results:

• Increased pressure leads to shorter O⋯O contacts in BA dimers, reducing the PT barrier.
• Hydrogen bond symmetrization was observed, but only when accounting for zero-point energy (ZPE) differences.
• A pressure-dependent decrease in the PT barrier was quantified.

Conclusions:

• Pressure effectively tunes the proton transfer barrier in solid benzoic acid.
• Zero-point energy is critical for accurately describing hydrogen bond symmetrization under compression.
• Findings suggest a universal scaling behavior for hydrogen bond symmetrization based on O⋯O distance in various systems.