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We propose the generalized initial velocity sampling algorithm at a transition state, in which the total initial kinetic energy and extra positive initial velocity along the reaction coordinate have been introduced to improve the accuracy and efficiency of nonadiabatic dynamics simulation. This sampling algorithm is very useful for chemical reactions with multiple transition states, e.g., two transition states in the thermolysis of four-membered heterocyclic peroxides. The dependence of the chemiexcitation yields, dissociation times, and other quantities on the total initial kinetic energy and extra positive initial velocity has been investigated. By taking different CASPT2 corrections and additional positive initial velocities into account, we found that the resulting triplet quantum yield matches the experimental result perfectly. In most ensembles, the secondary primary intersystem crossing, i.e., the first singlet excited state to the first triplet state, is a major direct production channel for the first triplet state product trajectories.
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Dissociation Time, Quantum Yield, and Dynamic Reaction Pathways in the Thermolysis of trans -3,4-Dimethyl-1,2-dioxetane
The thermolysis of trans-3,4-dimethyl-1,2-dioxetane is studied by trajectory surface hopping. The significant difference between long and short dissociation times is rationalized by frustrated dissociations and the time spent in triplet states. If the C−C bond breaks through an excited state channel, then the trajectory passes over a ridge of the potential energy surface of that state. The calculated triplet quantum yields match the experimental results. The dissociation half-times and quantum yields follow the same ascending order as per the product states, justifying the conjecture that the longer dissociation time leads to a higher quantum yield, proposed in the context of the methylation effect. The populations of the molecular Coulomb Hamiltonian and diagonal states reach equilibrium, but the triplet populations with different Sz components fluctuate indefinitely. Certain initial velocities, leading the trajectories to given product states, can be identified as the most characteristic features for sorting trajectories according to their product states.
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- PAR ID:
- 10515894
- Publisher / Repository:
- ACS
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry Letters
- Volume:
- 15
- Issue:
- 7
- ISSN:
- 1948-7185
- Page Range / eLocation ID:
- 1846 to 1855
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acs.jpclett.3c03578
