Concerted proton-electron transfer via vibration correlation function approach with effective anharmonicity: Beyond...

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Proton-coupled electron transfer (CPET) reactions are vital for energy conversion but are complex to model.
• Existing methods like MSC and MLJ neglect key quantum mechanical factors, leading to inaccuracies.
• These factors include proton-electron nonadiabatic dynamics, anharmonic potentials, and vibronic coupling.

Purpose of the Study:

• To introduce a new computational method, the vibration correlation function with effective anharmonicity (VCF-H).
• To systematically incorporate multidimensional vibronic coupling and Duschinsky transformations into CPET modeling.
• To provide a more accurate and physically transparent framework for studying CPET reactions.

Main Methods:

• Developed the VCF-H method, extending the VCF formalism.
• Incorporated multidimensional vibronic coupling, Duschinsky transformations, and anharmonic corrections.
• Applied VCF-H to gas-phase CPET model systems (phenoxyl/phenol and thymine-acrylamide complexes).

Main Results:

• Duschinsky coupling significantly impacts CPET rates, increasing them by orders of magnitude compared to MSC/MLJ.
• Classical treatment of non-transferring proton modes underestimates rate constants.
• Fully quantum mechanical treatment in VCF-H is essential for accurate rate predictions.

Conclusions:

• The VCF-H method offers a streamlined and transparent framework for modeling CPET reactions.
• Highlights the critical importance of multidimensional vibronic coupling and Duschinsky effects in CPET dynamics.
• Establishes a clearer theoretical relationship between VCF-H and existing MSC/MLJ formulations.