Collision-induced and complex-mediated roaming dynamics in the H + C2H4 → H2 + C2H3 reaction

Fu, Yanlin; Lu, Xiaoxiao; Han, Yong‐Chang; Fu, Bina; Zhang, Dong H.; Bowman, Joel M.

doi:10.1039/c9sc05951b

Cited by 32 publications

(38 citation statements)

References 37 publications

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“…Examples of potentials for six- and seven-atom chemical reactions, which are fits to tens of thousands or even 100 000 CCSD(T) energies, have also been reported. 1 , 3 , 4 , 7 , 8 …”

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confidence: 99%

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Breaking the Coupled Cluster Barrier for Machine-Learned Potentials of Large Molecules: The Case of 15-Atom Acetylacetone

Houston

Conte

et al. 2021

J. Phys. Chem. Lett.

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100

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Machine-learned potential energy surfaces (PESs) for molecules with more than 10 atoms are typically forced to use lower-level electronic structure methods such as density functional theory (DFT) and second-order Møller–Plesset perturbation theory (MP2). While these are efficient and realistic, they fall short of the accuracy of the “gold standard” coupled-cluster method, especially with respect to reaction and isomerization barriers. We report a major step forward in applying a Δ-machine learning method to the challenging case of acetylacetone, whose MP2 barrier height for H-atom transfer is low by roughly 1.1 kcal/mol relative to the benchmark CCSD(T) barrier of 3.2 kcal/mol. From a database of 2151 local CCSD(T) energies and training with as few as 430 energies, we obtain a new PES with a barrier of 3.5 kcal/mol in agreement with the LCCSD(T) barrier of 3.5 kcal/mol and close to the benchmark value. Tunneling splittings due to H-atom transfer are calculated using this new PES, providing improved estimates over previous ones obtained using an MP2-based PES.

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“…Examples of potentials for six- and seven-atom chemical reactions, which are fits to tens of thousands or even 100 000 CCSD(T) energies, have also been reported. 1 , 3 , 4 , 7 , 8 …”

mentioning

confidence: 99%

“…Both of these PESs were fit using permutationally invariant polynomial (PIP) regression. Examples of potentials for six- and seven-atom chemical reactions, which are fits to tens of thousands or even 100 000 CCSD(T) energies, have also been reported. ,,,, …”

mentioning

confidence: 99%

Breaking the Coupled Cluster Barrier for Machine-Learned Potentials of Large Molecules: The Case of 15-Atom Acetylacetone

Houston

Conte

et al. 2021

J. Phys. Chem. Lett.

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100

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“…There has been dramatic progress in using regression methods from machine learning (ML) to develop potential energy surfaces (PESs) for systems with more than five atoms, based on fitting thousands of CCSD(T) energies. [1][2][3][4] However, the CCSD(T) method, because it scales as N 7 where N is the system size, is too computationally demanding for PES fits of systems with more than 10 heavy atoms. (This number of atoms is rightly not considered a "large molecule" by many readers; however, it is used here as a computational boundary for the CCSD(T) method.)…”

Section: Introductionmentioning

confidence: 99%

“…Examples of potentials for 6 and 7-atom chemical reactions which are fits to tens or even hundred thousand CCSD(T) energies have also been reported. 1,3,4,7,8 The 10-atom CCSD(T)-barrier is due both to the steep scaling with N and the increasing dimensionality of the PES, which requires larger data sets. Thus, given the intense interest, and progress, in moving to larger molecules and clusters, where high-level methods are prohibitively expensive, the use of lower-level methods such as Density Functional Theory (DFT) and second-order Møller-Plesset perturbation (MP2) theory, is understandable.…”

Section: Introductionmentioning

confidence: 99%

Breaking the Coupled Cluster Barrier for Machine Learned Potentials of Large Molecules: The Case of 15-atom Acetylacetone

Qu,

Houston,

Conte

et al. 2021

Preprint

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Machine-learned potential energy surfaces (PESs) for molecules with more than 10 atoms are typically forced to use lower-level electronic structure methods such as density functional theory and second-order Møller-Plesset perturbation theory (MP2). While these are efficient and realistic, they fall short of the accuracy of the "gold standard" coupled-cluster method [CCSD(T)], especially with respect to reaction and isomerization barriers. We report a major step forward in using a ∆-machine learning method to the challenging case of acetlyacetone, whose MP2 barrier height for H-atom transfer is low by roughly 1.5 kcal/mol relative to the CCSD(T) barrier of 3.5 kcal/mol. From a database of 2151 LCCSD(T) energies, and training with as few as 430 energies, we obtain a new PES with a barrier in agreement with the LCCSD(T) one. Tunneling splittings due to H-atom transfer are calculated using this new PES, providing improved estimates over previous ones obtained using an MP2-based PES.

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“…Compared to TST method, QCT method examines the detailed characteristics of collision and energy transfer with a higher computing cost. Fu et al [20] reported a high-level computational study of roaming dynamics in the bimolecular combustion reaction H + C H = H + C H . It was learnt that the binary collision can lead to "collision-induced" roaming, i.e., the incident H radical roams over the C2H4 molecule before a hydrogen abstraction reaction occurs.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Abstraction/Addition Reactions in Soot Surface Growth

Chu

Shi²,

Wang³

et al. 2020

Preprint

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The hydrogen abstraction (HB) and addition reactions (HD) by H radicals are examined on a series of polycyclic aromatic hydrocarbon (PAH) monomers and models of quasi-surfaces using quasi-classical trajectory (QCT) method. The QCT results reproduce the rate constants of HB reactions on PAH monomers from density function theory (DFT) in the range of 1500-2700 K. The PAH size has a minor impact on the rates of HB reactions especially at temperatures beyond 2100 K. By contrast, HD reactions have a clear size dependence and a larger PAH yields a higher rate. It is also found that the preferred reaction pathway changing from HB to HD reactions at ~1900 K. The rates of surface HB and HD reactions exceed those in the gas phase by nearly a factor of magnitude. Further analysis on the detailed trajectory of QCT method reveals that about 50% of the surface reactions can be attributed to the events of surface diffusion, which depends on the local energy transfer in the gas-surface interactions. However, this phenomenon is not preferred in PAH monomers as expected. Our finding here highlights the misinterpretation of surface reactions as the product of the first collision between gaseous species and particle surface, and surface diffusion induced reactions should be accounted for in the rates of surface HB and HD reactions. Rate constants of HB and HD reactions on each reactive site (surface zig-zag, surface free-edge and pocket free-edge sites) are calculated by QCT method, which are recommended for the further development of surface chemistry models in soot formation.

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Collision-induced and complex-mediated roaming dynamics in the H + C₂H₄ → H₂ + C₂H₃ reaction

Abstract: Collision-induced and complex-mediated roaming mechanisms are revealed for an important bimolecular reaction in combustion.

Cited by 32 publications

References 37 publications

Breaking the Coupled Cluster Barrier for Machine-Learned Potentials of Large Molecules: The Case of 15-Atom Acetylacetone

Breaking the Coupled Cluster Barrier for Machine-Learned Potentials of Large Molecules: The Case of 15-Atom Acetylacetone

Breaking the Coupled Cluster Barrier for Machine Learned Potentials of Large Molecules: The Case of 15-atom Acetylacetone

Hydrogen Abstraction/Addition Reactions in Soot Surface Growth

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