A Nonequilibrium Molecular Dynamics Study of Infrared Perturbed Electron Transfer

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Molecular Dynamics

Background:

• Infrared (IR) excitation is known to influence electron-transfer kinetics in molecules.
• Understanding how vibrational energy affects electron transfer is crucial for controlling chemical reactions.

Purpose of the Study:

• To explore the molecular mechanisms by which vibrational excitation influences nonadiabatic electron transfer using simulations.
• To investigate the impact of IR excitation on electron transfer rates in specific molecular systems.

Main Methods:

• Utilized nonequilibrium molecular dynamics (NEqMD) simulations combined with electronic structure computations.
• NEqMD simulations incorporated nonequilibrium semiclassical initial conditions to model vibrationally excited molecules.
• Analyzed two molecular species: dimethylaniline-guanosine-cytidine-anthracene (DMA-GC-Anth) and 4-(pyrrolidin-1-yl)phenyl-2,6,7-triazabicyclo[2.2.2]octatriene-10-cyanoanthracen-9-yl (PP-BCN-CA).

Main Results:

• In DMA-GC-Anth, IR excitation and subsequent intramolecular vibrational energy redistribution (IVR) showed no significant change in donor-acceptor (DA) coupling.
• In PP-BCN-CA, IR excitation of the C═N bond altered bridge-mediated coupling for charge separation and recombination by approximately 30-40%.
• Demonstrated that IR excitation can significantly perturb charge-transfer processes at the molecular level.

Conclusions:

• The effect of IR excitation on electron transfer is molecule-specific.
• NEqMD simulations provide a powerful tool for investigating the influence of vibrational excitation on charge-transfer dynamics.
• This approach enables detailed molecular-scale exploration of IR effects on chemical processes.