Electron Transfer Assisted by Vibronic Coupling from Multiple Modes.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Electron transfer (ET) rate prediction is crucial for diverse applications like catalysis and solar energy.
• Marcus-Jortner-Levich (MJL) theory provides a model for ET rates, but its integration with density functional theory (DFT) for first-principles prediction remains a challenge.
• Previous methods often required approximations, such as using a single empirical frequency, limiting predictive accuracy.

Purpose of the Study:

• To develop a robust first-principles methodology for calculating electron transfer rates modulated by molecular vibrations.
• To overcome the computational cost associated with detailed vibrational analysis in ET rate calculations.
• To establish a predictive DFT-MJL approach without empirical parameters.

Main Methods:

• A novel framework combining density functional theory (DFT) with the Marcus-Jortner-Levich (MJL) equation.
• Utilizing Monte Carlo sampling to evaluate the full MJL equation across the entire space of thermally accessible vibrational modes.
• Avoiding approximations by considering the complete vibrational manifold, rather than condensing it to a single frequency.

Main Results:

• The developed DFT-MJL approach accurately predicts electron transfer rates over four orders of magnitude (10^6 - 10^10 s^-1).
• The method successfully circumvents the high computational cost typically associated with detailed vibrational mode analysis.
• Individual contributions of vibrational modes to the ET rate were illustrated, offering insights into their interplay with electronic states.

Conclusions:

• The presented framework provides accurate, parameter-free predictions of electron transfer rates, significantly advancing computational chemistry.
• This methodology enables a deeper understanding of how multiple vibrational modes influence electron transfer processes.
• The findings are broadly applicable to chemical systems where vibronic coupling governs electron transfer dynamics.