Nonadiabatic ring-polymer instanton rate theory: A generalized dividing-surface approach

Area of Science:

• Theoretical Chemistry
• Quantum Dynamics
• Chemical Reaction Theory

Background:

• Accurate nonadiabatic rate theory is crucial but challenging for arbitrary electronic coupling.
• Existing theories are limited to specific limits (Born-Oppenheimer or weakly coupled diabatic surfaces).
• Nuclear quantum effects like tunneling and zero-point energy are vital for reaction rates.

Purpose of the Study:

• Develop a generalized nonadiabatic instanton rate theory.
• Bridge the gap between existing adiabatic and diabatic rate theories.
• Provide a computationally efficient method for nonadiabatic reactions.

Main Methods:

• Utilized ring-polymer instanton theory with semiclassical approximations.
• Developed a tunable dividing surface to measure flux across nuclear and electronic coordinates.
• Extended Fermi's golden rule framework for nonadiabatic systems.

Main Results:

• The generalized theory accurately approximates quantum-mechanically exact rates.
• The method successfully bridges adiabatic and diabatic limits.
• The theory provides novel mechanistic insights into nonadiabatic reaction pathways.

Conclusions:

• The developed generalized nonadiabatic instanton rate theory offers a significant advancement.
• This approach provides accurate and computationally feasible calculations for nonadiabatic reactions.
• The theory enhances understanding of reaction mechanisms involving electronic transitions.