A systematic model study quantifying how conical intersection topography modulates photochemical reactions.

Area of Science:

• Photochemistry
• Computational Chemistry
• Molecular Dynamics

Background:

• Conical intersections are crucial for molecular photoreactivity and photostability.
• Their unique degenerate electronic states enable ultrafast nonadiabatic transfer.
• Understanding conical intersection topography is key to controlling photochemical processes.

Purpose of the Study:

• To investigate the impact of conical intersection topography on nonadiabatic dynamics.
• To simulate photochemical observables by varying vibrational mode frequencies.
• To define relationships between topography and photochemical outcomes.

Main Methods:

• Utilized an adaptable computational model to study conical intersections.
• Systematically varied vibrational mode frequencies in four classes of conical intersections.
• Simulated nonadiabatic dynamics and calculated decay rates, total yields, and product yields.

Main Results:

• Higher vibrational mode frequencies were found to reduce nonadiabatic transfer.
• Conversely, increased frequencies enhanced the rate of nonadiabatic transfer.
• Higher frequencies also led to increased photoproduct formation.

Conclusions:

• Conical intersection topography significantly influences photochemical reaction dynamics.
• Vibrational mode frequencies are a key factor in tuning nonadiabatic transfer and reaction outcomes.
• Findings can guide experimental control of photochemical reactions and molecular property tuning.