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Ab Initio Metadynamics Calculations Reveal Complex Interfacial Effects in Acetic Acid Deprotonation Dynamics

preprint
submitted on 27.01.2021, 05:43 and posted on 28.01.2021, 11:43 by Sohag Biswas, Bryan Wong
Acid-base reactions play a central role in solution chemistry, with carboxylic acids being particularly important in atmospheric chemical processes. In this work, we harness metadynamics calculations with Born-Oppenheimer molecular dynamics (BOMD) simulations to understand deprotonation dynamics of acetic acid (CH3COOH) in both bulk and air-water interfacial environments. Collective variables are carefully chosen in our well-tempered metadynamics simulations to capture the deprotonation process in various aqueous configurations. Our findings show that the free energy barrier for deprotonation of acetic acid at the air-water interface is lower than in the bulk, in accordance with the available experimental data. Furthermore, our well-tempered metadynamics calculations suggest that the variations in free energy are primarily due to intricate solvation shell effects.

Funding

Department of Energy, Office of Science, Award No. DE-SC0016269

History

Email Address of Submitting Author

usagi@alum.mit.edu

Institution

University of California, Riverside

Country

United States

ORCID For Submitting Author

0000-0002-3477-8043

Declaration of Conflict of Interest

no conflict of interest

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