A chemical dynamics study of the reaction of the methylidyne radical (CH, X2Π) with dimethylacetylene (CH3CCCH3, X1A1g)

He, Chao; Fujioka, Kazuumi; Nikolayev, Anatoliy A.; Zhao, Long; Doddipatla, Srinivas; Azyazov, Valeriy N.; Mebel, Alexander M.; Sun, Rui; Kaiser, Ralf I.

doi:10.1039/d1cp04443e

Cited by 14 publications

(25 citation statements)

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“…Since the cost of different ab initio methods scales differently with the number ( N ) of basis functions (roughly N 4 for DFTs and N 5 for MP2) and the number of basis functions tested in this study spans a large range (between 26 for LANL2DZ and 155 for aug-cc-pVTZ), the cost of tested candidate methods varies dramatically. As previous AIMD studies have demonstrated, their results are extremely sensitive with respect to the method (e.g., MP2 vs DFT). − Further, since the computationally efficient method is selected based on optimized structures, while AIMD simulations traverse through unoptimized structure, it is possible that the computationally efficient method with the smallest RMSD performs poorly in AIMD. ,, Behaviors such as convergence failures, total energy jumps, and/or unphysical charge distributions have been previously reported for AIMD with DFTs. , Therefore, one DFT functional, the rCAM-B3LYP functional, and one MP2 method, FC-MP2, are recommended. For the former, rCAM-B3LYP functional reports the overall smallest RMSD with pc-2 (5.3 kJ/mol, 105 basis functions), followed by cc-pVDZ (5.8 kJ/mol, 55 basis functions) and Sapporo-DZP-2012 (6.0 kJ/mol, 80 basis functions).…”

Section: Resultsmentioning

confidence: 99%

“…64−66 Further, since the computationally efficient method is selected based on optimized structures, while AIMD simulations traverse through unoptimized structure, it is possible that the computationally efficient method with the smallest RMSD performs poorly in AIMD. 15,67,68 Behaviors such as convergence failures, total energy jumps, and/or unphysical charge distributions have been previously reported for AIMD with DFTs. 15,67 Therefore, one DFT functional, the rCAM-B3LYP functional, and one MP2 method, FC-MP2, are recommended.…”

Section: Selecting a Computationally Efficientmentioning

confidence: 85%

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The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision

2022

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Recently, the HBr + + HCl bimolecular reaction has been exploited by guided ion beam studies to probe the effect of rotational excitations and collision energies on the dynamics of the ion−molecule reactions. The current manuscript employs high-level ab initio calculations and reports the potential energy of pathways leading to various products, including HBr + HCl + , H 2 Cl + + Br, H 2 Br + + Cl, and H 2 + BrCl + . The study shows that the intermediates involved in this reaction are connected by lowlying transition states, thus frequent isomerizations and diverse products are expected. Further, this manuscript screens the performance of 192 different combinations of computationally efficient methods and basis sets in order to identify the optimal quantum chemical method for further dynamics simulations.

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Section: Resultsmentioning

confidence: 99%

Section: Selecting a Computationally Efficientmentioning

confidence: 85%

The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision

2022

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“…Following the astrophysical detection of c-C 3 HC 2 H (Cernicharo et al 2021), a mechanistic study of its formation found that c-C 3 HC 2 H may form through a gas-phase reaction between c-C 3 H 2 and the ethynyl radical (Fortenberry 2021). These results open a veritable Pandora's box for further astrochemical analysis regarding the formation of c-C 3 H 2 and its family of derivatives (He et al 2022;Yang et al 2021).…”

Section: Introductionmentioning

confidence: 95%

The Formation of Monosubstituted Cyclopropenylidene Derivatives in the Interstellar Medium via Neutral–Neutral Reaction Pathways

Flint

Fortenberry

2022

ApJ

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Five substituted cyclopropenylidene derivatives (c-C3HX, X=CN, OH, F, NH2), all currently undetected in the interstellar medium (ISM), are found herein to have mechanistically viable, gas-phase formation pathways through neutral–neutral additions of ·X onto c-C3H2. The detection and predicted formation mechanism of c-C3HC2H introduces a need for the chemistry of c-C3H2 and any possible derivatives to be more fully explored. Chemically accurate CCSD(T)-F12/cc-pVTZ-F12 calculations provide exothermicities of additions of various radical species to c-C3H2, alongside energies of submerged intermediates that are crossed to result in product formation. Of the novel reaction mechanisms proposed, the addition of the cyano radical is the most exothermic at -16.10 kcal mol−1. All five products are found to or are expected to have at least one means of associating barrierlessly to form a submerged intermediate, a requirement for the cold chemistry of the ISM. The energetically allowed additions arise as a result of the strong electrophilicity of the radical species as well as the product stability gained through substituent-ring conjugation.

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“…The chemical scheme of formation of these species is based on neutral-neutral reactions and is discussed in detail in Appendix D. Briefly, reactions of CCH and CN with c-C 5 H 6 and C 6 H 6 lead to the CCH/CN derivatives of each cycle (Balucani et al , 1999;Jones et al , 2010). The formation of the precursor hydrocarbon cycles c-C 5 H 6 and C 6 H 6 relies on reactions between small hydrocarbon radicals and butadiene (CH 2 CHCHCH 2 ), which acts as a key species that opens the chemistry to hydrocarbon cycles at 10 K (He et al , 2020a;Jones et al , 2011). Additional routes to the CCH/CN derivatives of c-C 5 H 6 involve reactions of C 3 H/C 2 N with butadiene.…”

Section: Chemistry Of Cycles In Tmc-1mentioning

confidence: 99%

Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles

Cernicharo,

Agundez,

Kaiser

et al. 2021

Preprint

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We report the detection of two isomers of ethynyl cyclopentadiene (c-C 5 H 5 CCH), namely 1-and 2-ethynyl-1,3-cyclopentadiene, in the direction of TMC-1. We derive column densities of (1.4±0.2)×10 12 cm −2 and (2.0±0.4)×10 12 cm −2 , respectively, for these two cyclopentadiene derivatives, which imply that they are about ten times less abundant than cyclopentadiene. We also report the tentative detection of ethynyl benzene (C 6 H 5 CCH), for which we estimate a column density of (2.5±0.4)×10 12 cm −2 . We derived abundances for the corresponding cyano derivatives of cyclopentadiene and benzene and found values significantly lower than previously reported. The rotational temperature of the ethynyl and cyano derivatives of these cycles is about 9 K, that is, very close to the gas kinetic temperature of the cloud. The abundance ratio of the 1-and 2-isomers of ethynyl cyclopentadiene is 1.4±0.5, while for the two isomers of cyano cyclopentadiene it is 2.4±0.6. The relative abundances of CCH over CN derivatives is 7.7±2.2 for cyclopentadiene, which probably reflects the abundance ratio of the radicals CCH and CN; this ratio is only 2.1±0.5 for benzene, which suggests that additional reactions besides cyano radicals with benzene are involved in the formation of benzonitrile. The formation of these cycles is reasonably well accounted for through a chemical scheme based on neutral-neutral reactions. It is predicted that benzene should be as abundant as cyclopentadiene in TMC-1.

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A chemical dynamics study of the reaction of the methylidyne radical (CH, X²Π) with dimethylacetylene (CH₃CCCH₃, X¹A_1g)

Abstract: The gas-phase reaction of the methylidyne (CH; X2Π) radical with dimethylacetylene (CH3CCCH3; X1A1g) was studied at a collision energy of 20.6 kJ mol-1 under single collision conditions with experimental results...

Cited by 14 publications

References 108 publications

The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision

The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision

The Formation of Monosubstituted Cyclopropenylidene Derivatives in the Interstellar Medium via Neutral–Neutral Reaction Pathways

Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles

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A chemical dynamics study of the reaction of the methylidyne radical (CH, X2Π) with dimethylacetylene (CH3CCCH3, X1A1g)

Abstract: The gas-phase reaction of the methylidyne (CH; X2Π) radical with dimethylacetylene (CH3CCCH3; X1A1g) was studied at a collision energy of 20.6 kJ mol-1 under single collision conditions with experimental results...

Cited by 14 publications

References 108 publications

The Potential Energy Profile of the HBr+ + HCl Bimolecular Collision

The Potential Energy Profile of the HBr+ + HCl Bimolecular Collision

The Formation of Monosubstituted Cyclopropenylidene Derivatives in the Interstellar Medium via Neutral–Neutral Reaction Pathways

Discovery of two isomers of ethynyl cyclopentadiene in TMC-1: Abundances of CCH and CN derivatives of hydrocarbon cycles

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Product

Resources

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A chemical dynamics study of the reaction of the methylidyne radical (CH, X²Π) with dimethylacetylene (CH₃CCCH₃, X¹A_1g)

The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision

The Potential Energy Profile of the HBr⁺ + HCl Bimolecular Collision