Automated identification and calculation of prompt effects in kinetic mechanisms using statistical models

Maffei, Luna Pratali; Moore, Kevin B.; Georgievskii, Yuri; Mulvihill, Clayton R.; Elliott, Sarah N.; Cho, Jaeyoung; Sivaramakrishnan, R.; Faravelli, Tiziano; Klippenstein, Stephen J.

doi:10.1016/j.combustflame.2022.112422

Cited by 5 publications

(9 citation statements)

References 52 publications

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“…Prompt effects were estimated with statistical models using AutoMech. , The automated procedure was extensively explained in a recent publication . In particular, in this work the ρ DOS model was adopted: the density of states of the excited product fragments from each H-abstraction reaction allows the derivation of the energy distribution of the rovibrationally excited C 6 H 7 isomer.…”

Section: Methodsmentioning

confidence: 99%

“…The relevance of this mechanism is expected to increase with the temperature and the reaction exothermicity. This aspect was investigated here using the recent automation of the calculation of prompt effects through a statistical model that has significantly simplified the process . Finally, it is interesting to compare the rate constants determined using several automatized features of the code we recently developed to study kinetics, EStokTP, inclusive also of corrections for internal coordinate treatments, with those performed with literature approaches.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Methylcyclopentadiene Reactivity: Abstraction Reactions and Methylcyclopentadienyl Radical Unimolecular Decomposition

et al. 2023

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Understanding the reactivities of methylcyclopentadiene and the methylcyclopentadienyl radical is important in order to improve our comprehension of the chemical kinetics leading to the formation, decomposition, and growth of the first aromatic ring, as it has been shown that five-membered-ring species are important intermediates in the reaction kinetics of aromatic species. In this work, the rate constants of some key H-abstraction reactions from methylcyclopentadiene to produce the methylcyclopentadienyl radical and the formation of fulvene and benzene from the latter are theoretically determined. Rate constants are evaluated using the ab initio transition state theory-based master equation approach, determining structures and Hessians of all stationary points at the ωB97X-D/aug-cc-pVTZ level, energies at the CCSD(T) level extrapolated to the complete basis set limit, RRKM rate constants using conventional and variational transition state theory, and phenomenological rate constants through the solution of the one-dimensional master equation. Variational corrections are determined in both internal and Cartesian coordinates, and it is found that the choice of the coordinate system can impact the accuracy of the calculated rate constants by up to a factor of 4 for H-abstraction reactions and 2 for the unimolecular decomposition of the methylcyclopentadienyl radical. The calculated rate constants are in good agreement with the available literature data. Prompt dissociation of methylcyclopentadienyl radicals accessed following H-abstraction from methylcyclopentadiene was also investigated, and the corresponding rate constants were determined; the results show that prompt dissociation plays a key role under combustion conditions. Finally, lumping of theoretically derived rate constants to account for methylcyclopentadiene ⇄ methylcyclopentadienyl tautomerism allowed the derivation of a simplified set of rate constants suitable to be inserted into kinetic mechanisms.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of Methylcyclopentadiene Reactivity: Abstraction Reactions and Methylcyclopentadienyl Radical Unimolecular Decomposition

et al. 2023

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“…59 Another difficult aspect is the automatic treatment of master equations coupled via the formation of hot products that react further before establishing their Boltzmann distribution via collisions with the bath gas. Maffei et al 60 are developing an approach to handle such cases.…”

Section: Kineticsmentioning

confidence: 99%

Automated Reaction Kinetics of Gas-Phase Organic Species over Multiwell Potential Energy Surfaces

et al. 2023

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Automation of rate-coefficient calculations for gas-phase organic species became possible in recent years and has transformed how we explore these complicated systems computationally. Kinetics workflow tools bring rigor and speed and eliminate a large fraction of manual labor and related error sources. In this paper we give an overview of this quickly evolving field and illustrate, through five detailed examples, the capabilities of our own automated tool, KinBot. We bring examples from combustion and atmospheric chemistry of C-, H-, O-, and N-atom-containing species that are relevant to molecular weight growth and autoxidation processes. The examples shed light on the capabilities of automation and also highlight particular challenges associated with the various chemical systems that need to be addressed in future work.

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“…One interesting preliminary finding is that the fully statistical models lead to greatly enhanced prompt dissociation effects over f ne based estimates. 149…”

Section: Chemical Conversions and Rrkm Theorymentioning

confidence: 99%

“…Currently, the coupling of an arbitrary sequence of dissociations initiated by a single bimolecular reaction has been implemented and is being tested within AutoMech. 149 The inclusion of a sequence of bimolecular reactions is a bit more complicated due to the need to couple multiple PESs in order to properly treat the dissociations back to reactants. Lei and Burke recently presented an approximate methodology for handling that process together with a set of scripts for doing so.…”

Section: Chemical Conversions and Rrkm Theorymentioning

confidence: 99%

Spiers Memorial Lecture: Theory of unimolecular reactions

Klippenstein

2022

Faraday Discuss.

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Automated identification and calculation of prompt effects in kinetic mechanisms using statistical models

Cited by 5 publications

References 52 publications

Investigation of Methylcyclopentadiene Reactivity: Abstraction Reactions and Methylcyclopentadienyl Radical Unimolecular Decomposition

Investigation of Methylcyclopentadiene Reactivity: Abstraction Reactions and Methylcyclopentadienyl Radical Unimolecular Decomposition

Automated Reaction Kinetics of Gas-Phase Organic Species over Multiwell Potential Energy Surfaces

Spiers Memorial Lecture: Theory of unimolecular reactions

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