Redox Potentials from Ab Initio Molecular Dynamics and Explicit Entropy Calculations: Application to Transition...

Area of Science:

• Computational Chemistry
• Electrochemistry
• Quantum Mechanics

Background:

• Accurate prediction of redox potentials is crucial for understanding and designing electrochemical systems.
• Existing methods often rely on experimental data or approximations, limiting their predictive power.

Purpose of the Study:

• To present a robust, first-principles methodology for calculating redox potentials.
• To validate the approach across a diverse set of redox couples in different solvents.
• To establish a computationally efficient and statistically stable method for free energy calculations.

Main Methods:

• Ab initio molecular dynamics (MD) simulations with all-atom explicit solvation.
• Application of the two-phase thermodynamic (2PT) model.
• Utilization of electrostatic potentials for referencing the absolute electrochemical scale.

Main Results:

• Accurate computation of reduction potentials for Cr, V, Ru, Sn, Cu, Fe, and ferrocene derivatives in aqueous solution and acetonitrile.
• Demonstrated the necessity of quantum-mechanical simulations for capturing solvent dynamics.
• Achieved excellent agreement with experimental data, with root-mean-square deviations as low as 0.457 V.

Conclusions:

• The proposed methodology provides a reliable, experiment-free route to redox potential estimation.
• Computational efficiency and statistical stability are key advantages.
• The accuracy is primarily limited by the chosen exchange-correlation functional's ability to describe specific molecular complexes.