Vibrational distribution and dynamics study of the HCN(v
            1, v
            2, v
            3) product in the CN + CH4 hydrogen abstraction reaction

Espinosa‐García, J.; García-Bernáldez, J. C.

doi:10.1007/s00214-017-2155-2

Cited by 2 publications

(5 citation statements)

References 35 publications

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“…At 298 K on the QCT/PES-2023 results, the NMA analysis reported more than 300 populated HCN(v1,v2,v3) vibrational states, and 150 states with population > 0.1 %, the most populated state, HCN(1, 0, 1), presenting a population of only 8%. This picture is similar to those obtained in our previous work on the CN + CH4 reaction, 39 and they clearly show that these low populations will represent a challenge in experiments. Figure 5 presents the lowest bending vibrational states, which show practically Gaussian distributions of the bending mode (i).…”

Section: Results and Dicussionsupporting

confidence: 90%

“…The small fraction of energy deposited as vibration in the C2H5 co-product, 12%, suggests that this product will appear practically in its vibrational ground-state. This tendency is similar to that found for the CN + CH4 reaction: 39 52, 8, 15, 7, and 18%, respectively, (note that, strictly speaking, these values correspond to a fixed collision energy of 1.0 kcal mol -1 ) 39 showing that these reactions with alkanes present similar dynamic behaviour.…”

Section: Results and Dicussionsupporting

confidence: 82%

“…These last two approaches (or a purely quantum treatment, when this is possible) are affordable and realistic when few product vibrational states are populated; however, this is not the case for the HCN(v1,v2,v3) product in the title reaction, where many vibrational states are populated with low individual population (see below in Results), and in these conditions the SB approach is advisable. This good behaviour was found in previous studies for the CN + CH4  HCN(v1,v2,v3) + CH3 reaction 39 and for the OH + CO → H + CO2(v1,v2,v3) reaction, 40,41 where the CO2 product also presented a large number of populated vibrational states, and where the SB and the more expensive 1GB approaches gave similar populations. A different picture was found when few vibrational states were populated.…”

Section: Theoretical Tools: Quasi-classical Trajectory Calculations A...supporting

confidence: 84%

“…Finally, the Legendre moment method 47 was used to fit the DCS and to smooth this histogram. Figure 10 plots the PADs for the title reaction (solid line) together with the scattering angle for the CN + CH4 reaction obtained by our group using PES-2017, both at 298 K. 39 Both distributions present a clear backward distribution, associated with a rebound mechanism, clearer in the case of methane reaction. This behaviour is related with the scattering angle/impact parameter relation, i.e., small impact parameters favour backward scattering.…”

Section: And Morris Et Al's Resultsmentioning

confidence: 99%

“…Now, we have quantitatively analysed this suggestion for the CN + methane and ethane reactions. Figure 6 shows the variation of the energy as a function of the NC…H'…R bending angle in the saddle point for both reactions using analytical surfaces from our lab, PES-2023, for the ethane reaction (present work) and PES-2017 25,39 for the methane reaction. Both reactions present similar behaviour, showing soft transition state structures, small dependence with the bending angle, and differences between them of only 0.05 kcal mol -1 at an angle deviation of 30º with respect to the saddle point geometry.…”

Section: And Morris Et Al's Resultsmentioning

confidence: 99%

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The CN + C2H6 reaction. Dynamics study based on an analytical full-dimensional potential energy surface.

Espinosa‐García

Rangel

2023

Preprint

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The hydrogen abstraction reaction of the cyano radical with molecules of ethane presents interest in the chemistry from ultra-cold to combustion environments, especially with regard to HCN(v) product vibrational distribution. In order to understand its dynamics a new analytical full-dimensional potential energy surface was developed, named PES-2023. It uses a combination of valence bond and mechanic molecular terms as functional form, fitted to high-level ab initio calculations at the explicitly correlated CCSD(T)-F12/aug-cc-pVTZ level on a reduced and selected number of points describing the reactive process. The new surface showed a continuous and smooth behaviour, describing reasonably the topology of the reaction: high exothermicity, low barrier and presence of intermediate complexes in the entrance and exit channels. Using quasi-classical trajectory calculations (QCT) on the new PES-2023, a dynamics study was performed at room temperature, with special emphasis on the HCN(v1,v2,v3) product stretching and bending vibrational excitations, and the results compared with the experimental evidence, which presented discrepancies in the bending excitation. The available energy was mostly deposited as HCN(v) vibrational energy, with the vibrational population inverted in the CH stretching mode and not inverted in the CN stretching and bending modes, thus simulating the experimental evidence. Other dynamics properties at room temperature were also analysed; cold rotational energy distribution was found, associated with a linear and soft transition state, and backward scattering distribution, associated with a rebound mechanism.

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Section: Results and Dicussionsupporting

confidence: 90%

Section: Results and Dicussionsupporting

confidence: 82%

Section: Theoretical Tools: Quasi-classical Trajectory Calculations A...supporting

confidence: 84%

Section: And Morris Et Al's Resultsmentioning

confidence: 99%

Section: And Morris Et Al's Resultsmentioning

confidence: 99%

See 3 more Smart Citations

The CN + C2H6 reaction. Dynamics study based on an analytical full-dimensional potential energy surface.

Espinosa‐García

Rangel

2023

Preprint

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The CN(X 2Σ+) + C2H6 reaction: Dynamics study based on an analytical full-dimensional potential energy surface

Espinosa-Garcia,

Rangel

2023

The Journal of Chemical Physics

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The hydrogen abstraction reaction of the cyano radical with molecules of ethane presents some interesting points in the chemistry from ultra-cold to combustion environments especially with regard to HCN(v) product vibrational distribution. In order to understand its dynamics, a new analytical full-dimensional potential energy surface was developed, named PES-2023. It uses a combination of valence bond and mechanic molecular terms as the functional form, fitted to high-level ab initio calculations at the explicitly correlated CCSD(T)-F12/aug-cc-pVTZ level on a reduced and selected number of points describing the reactive process. The new surface showed a continuous and smooth behavior, describing reasonably the topology of the reaction: high exothermicity, low barrier, and presence of intermediate complexes in the entrance and exit channels. Using quasi-classical trajectory calculations (QCT) on the new PES-2023, a dynamics study was performed at room temperature with special emphasis on the HCN(v1,v2,v3) product stretching and bending vibrational excitations, and the results were compared with the experimental evidence, which presented discrepancies in the bending excitation. The available energy was mostly deposited as HCN(v) vibrational energy with the vibrational population inverted in the CH stretching mode and not inverted in the CN stretching and bending modes, thus simulating the experimental evidence. Other dynamics properties at room temperature were also analyzed; cold rotational energy distribution was found, associated with a linear and soft transition state, and backward scattering distribution was found, associated with a rebound mechanism.

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Vibrational distribution and dynamics study of the HCN(v 1, v 2, v 3) product in the CN + CH4 hydrogen abstraction reaction

Cited by 2 publications

References 35 publications

The CN + C2H6 reaction. Dynamics study based on an analytical full-dimensional potential energy surface.

The CN + C2H6 reaction. Dynamics study based on an analytical full-dimensional potential energy surface.

The CN(X 2Σ+) + C2H6 reaction: Dynamics study based on an analytical full-dimensional potential energy surface

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