Dissection of the multichannel reaction of acetylene with atomic oxygen: from the global potential energy surface to rate coefficients and branching dynamics

Zuo, Junxiang; Chen, Qixin; Hu, Xuedong; Guo, Hua; Xie, Daiqian

doi:10.1039/c8cp07084a

Cited by 11 publications

(15 citation statements)

References 44 publications

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“…Figure 1 displays geometries of all stationary points and their energies relative to the reactant asymptote on the PIP-NN PES in our previous work [ 29 ]. The addition of the oxygen atom onto a C atom in acetylene takes place on the ground state PES via a shallow pre-reaction well (Int1) and a barrier (TS1), leading to intermediate complex Int2 (or Int3).…”

Section: Resultsmentioning

confidence: 99%

“…Once the energy redistribution occurs, the energy along the reaction coordinate is insufficient for the molecule to overcome the following barrier. Therefore, a microcanonical equilibrium between the two isomers is established [ 25 , 29 , 45 ]. After that, confronted with different kinds of exit channel barriers, the complex decomposes into different fragments.…”

Section: Resultsmentioning

confidence: 99%

“…The kinetic and dynamic properties for this reaction have been measured and calculated over a wide temperature range using various techniques [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Until recently, the experimental rate constants and branching ratios (BRs) have been confirmed by quasi-classical trajectory calculations based on the global potential energy surface (PES) at UCCSD(T)-F12b/VTZ-F12 level developed by our group [ 29 ]. The reaction pathways are quite complex, consisting of seven transition states and four intermediates, as shown in Figure 1 .…”

Section: Introductionmentioning

confidence: 99%

“…However, Nguyen et al [ 25 ] had found that product yields calculated from conventional RRKM theory depart from the experimental branching fractions (~80% R1 and ~20% R2) [ 22 ] and indicated that the rate of internal-rotation isomerization (

) was hampered by non-statistical energy partitioning, which implied that the statistical RRKM theory failed for certain intermediate steps. In our previous work [ 29 ], we classified trajectories by the propagation time and found that the two complexes (Int2 and Int3) could achieve a microcanonical equilibrium in slow reactions, but such an equilibrium was not established in fast reactions. In light of these studies, it is clear that the available energy is redistributed at all internal degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

“…To improve our understanding of the kinetics of the title reaction, in this work we reported a detailed quasi-classical trajectory (QCT) study of the O( 3 P) + C 2 H 2 reaction on the recently developed PIP-NN PES [ 29 ], focusing on the complex-forming mechanism and energy distribution in the reaction. We investigated the effect on reactivity by vibrational excitation of C 2 H 2 and extracted the final state information of the products for analyzing the effects of dynamics and statistics on the reaction.…”

Section: Introductionmentioning

confidence: 99%

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Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

et al. 2022

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The O(3P) + C2H2 reaction plays an important role in hydrocarbon combustion. It has two primary competing channels: H + HCCO (ketenyl) and CO + CH2 (triplet methylene). To further understand the microscopic dynamic mechanism of this reaction, we report here a detailed quasi-classical trajectory study of the O(3P) + C2H2 reaction on the recently developed full-dimensional potential energy surface (PES). The entrance barrier TS1 is the rate-limiting barrier in the reaction. The translation of reactants can greatly promote reactivity, due to strong coupling with the reaction coordinate at TS1. The O(3P) + C2H2 reaction progress through a complex-forming mechanism, in which the intermediate HCCHO lives at least through the duration of a rotational period. The energy redistribution takes place during the creation of the long-lived high vibrationally (and rotationally) excited HCCHO in the reaction. The product energy partitioning of the two channels and CO vibrational distributions agree with experimental data, and the vibrational state distributions of all modes of products present a Boltzmann-like distribution.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

et al. 2022

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Collaborative control of branching ratio in the O + HO₂ → OH + O₂ reaction via vibrational and rotational excitation

Chen

Xie

2022

J Chinese Chemical Soc

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To understand the effect of different vibrational and rotational modes of reactant to enhance the reactivity of the O + HO2 → OH + O2 reaction, we revisited this important atmospheric reaction. We report here a quasi‐classical trajectory (QCT) study of the reaction dynamics on a recently developed full‐dimensional potential energy surface (PES). Our previous work has indicated that this reaction has two pathways, the H abstraction (HA) channel and the O abstraction (OA) channel, which lead to totally different product energy distribution. In this work, we identified that the vibrational excitation of the OH stretching (v1) mode of HO2 is the switch of the HA channel at low collision energy; meanwhile, the rotational excitation can also greatly change the branching ratio of the two pathways. With the excitation of v1 mode, the original negligible HA channel controlled by the tight transition state becomes quite important. This work presents an approach to control the branching ratio via collaboration between vibrational and rotational excitation and will enrich the knowledge of the O + HO2 reaction in atmospheric chemistry and physics.

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Data Quality, Data Sampling and Data Fitting: A Tutorial Guide for Constructing Full-Dimensional Accurate Potential Energy Surfaces (PESs) of Molecules and Reactions

Li,

Liu

2023

Challenges and Advances in Computational Chemistry and Physics

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However, the direct dynamics on the B3LYP/6-31G(d) surface, starting from the transition state with additional 0.6 kcal mol -1 deposited into the reaction coordinate, showed that the reaction took place mildly without hitting the repulsive wall but following the MEP. 34 Such a typical reactive trajectory is shown in Figure 1 by the gray (short dot) line.Significant computing costs can be saved by first constructing a high-quality PES based on accurate but expensive ab initio points covering all dynamically relevant regions. However, it is not an easy task to obtain reliable full-dimensional PESs, whose topology is complicated with reactants and products, saddle points and intermediates. As discussed above, a set of molecular configurations need be sampled first and their electronic energies (and / or forces) are computed at an appropriate level of theory. For a molecular system with Natom atoms (Natom ≥ 3), the full-dimensional PES is dependent on 3Natom -6 molecular intramolecular coordinates. The sampling size increases remarkably with the size of the system. Thanks to the huge development in electronic structure theory and the rapid progress in computing power, it is now straightforward to calculate reliable energies of hundreds of thousands of configurations. There are many electronic structure methods of varying accuracies and computing speeds, such as the Hartree-Fock method, the Moller-Plesset (MPn) perturbation methods, 35,36 and more sophisticated electron correlation methods, including the highly accurate coupled cluster method (e.g. CCSD(T)), 37 the configuration interaction method, 38 the complete-active-space self-consistent field (CASSCF) [39][40][41] or its variants, CASPT2, CASPT3, and the multi-reference configuration interaction method (MRCI). [41][42][43] Generally, with a bigger basis set and more sophisticated post-Hartree-Fock electron correlation treatment, the result is generally more reliable. Recently, Dawes and his coworkers have reviewed recent developments in single-and multireference electronic structure methods that are used to obtain accurate energies for constructing global molecular PESs. 44 Nonetheless, one has to perform comprehensive tests to choose an appropriate electronic structure method for good and consistent description of all sampling data with acceptable calculation cost.

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Dissection of the multichannel reaction of acetylene with atomic oxygen: from the global potential energy surface to rate coefficients and branching dynamics

Abstract: A global potential energy surface for the O(3P) + C2H2 reaction is developed and the quasi-classical trajectory study on the potential energy surface reproduce the rate coefficient and product branching ratio.

Cited by 11 publications

References 44 publications

Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

Collaborative control of branching ratio in the O + HO₂ → OH + O₂ reaction via vibrational and rotational excitation

Data Quality, Data Sampling and Data Fitting: A Tutorial Guide for Constructing Full-Dimensional Accurate Potential Energy Surfaces (PESs) of Molecules and Reactions

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Dissection of the multichannel reaction of acetylene with atomic oxygen: from the global potential energy surface to rate coefficients and branching dynamics

Abstract: A global potential energy surface for the O(3P) + C2H2 reaction is developed and the quasi-classical trajectory study on the potential energy surface reproduce the rate coefficient and product branching ratio.

Cited by 11 publications

References 44 publications

Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

Dissection of the Multichannel Reaction O(3P) + C2H2: Differential Cross-Sections and Product Energy Distributions

Collaborative control of branching ratio in the O + HO2 → OH + O2 reaction via vibrational and rotational excitation

Data Quality, Data Sampling and Data Fitting: A Tutorial Guide for Constructing Full-Dimensional Accurate Potential Energy Surfaces (PESs) of Molecules and Reactions

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Collaborative control of branching ratio in the O + HO₂ → OH + O₂ reaction via vibrational and rotational excitation