Transition Path Flight Times and Nonadiabatic Electronic Transitions

Area of Science:

• Quantum dynamics
• Chemical physics
• Computational chemistry

Background:

• Understanding nonadiabatic molecular dynamics is crucial for chemical reaction mechanisms.
• Accurate calculation of transition path times provides insights into quantum effects like tunneling and resonances.
• The Fewest Switches Surface Hopping (FSSH) method is a common approach for simulating nonadiabatic dynamics.

Purpose of the Study:

• To investigate transition path flight times in scattering on two electronic surfaces.
• To reveal quantum effects, including resonance lifetimes and nonclassical passage times.
• To assess the reliability of the FSSH method for calculating transition path times.

Main Methods:

• Numerically exact time propagation for computing flight times.
• Comparison of exact results with those from the Fewest Switches Surface Hopping (FSSH) method.
• Analysis of scattering on two electronic surfaces with a single crossing.

Main Results:

• Nonadiabatic effects were found to often increase flight times.
• The FSSH method accurately predicts transition path times only for classically allowed scattering.
• FSSH fails to accurately predict times and transition probabilities when quantum effects like tunneling and resonances dominate.

Conclusions:

• Flight time measurements offer valuable time-domain insights into quantum effects in nonadiabatic scattering.
• Methods neglecting quantum interference effects have limitations.
• The FSSH method's accuracy is limited in regimes dominated by quantum phenomena.