Quantum dynamics study reveals strong nonadiabatic effects in the C(1D) + D2 reaction, suggesting that additional electronic states are essential to reproduce experimental rates.
Key Points
Construct global diabatic potential energy surfaces for the 1 1A′ and 2 1A′ electronic states of the CH2 system and evaluate adiabatic versus nonadiabatic reaction dynamics for the C(1D) + D2 reaction.
Computed ab initio electronic energies using the MRCI-F12 method with the aug-cc-pVTZ basis set for both carbon and hydrogen atoms.
Fit global diabatic potential energy surfaces using an artificial neural network combined with a symmetry-constrained sin(α) function.
Carried out both adiabatic and nonadiabatic quantum scattering calculations to derive reaction probabilities, integral cross sections, and thermal rate constants.
Nonadiabatic dynamics yielded higher reaction probabilities and cross sections at low collision energies, whereas adiabatic values exceeded them at higher energies.
Nonadiabatic calculations exhibited closer agreement with experimental trends than adiabatic models, confirming the importance of nonadiabatic coupling within the A′ manifold.
Absolute calculated rate constants remained systematically lower than recent experimental values, indicating that contributions from the unmodeled 1 1A″ state are necessary to capture the full reaction rate.