Dynamics of the Simplest Reaction of a Carbon Atom in a Tetrahedral Environment

Camden, Jon P.; Bechtel, Hans A.; Zare, Richard N.

doi:10.1002/anie.200352642

Cited by 39 publications

(57 citation statements)

References 28 publications

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“…13 Clearly, a more detailed picture of the differential cross section is desirable but it will have to await more experimental work. Still, the present analysis is able to provide a reliable estimate of the gross shape of the angular distribution.…”

Section: Resultsmentioning

confidence: 99%

“…One recent experiment by Camden, Bechtel, and Zare 13 suggested that a stripping mechanism competes with the rebound mechanism. In a more recent work, 14 we compared the angular distributions from quasi-classical trajectory (QCT) to the experimental results for a center-of-mass collision energy (E col ) of 1.2 eV and proposed a mechanism to account for this behavior.…”

Section: Introductionmentioning

confidence: 99%

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H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

Camden

Bechtel

et al. 2005

J. Phys. Chem. A

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We compare experimental photoloc measurements and quasi-classical trajectory calculations of the integral cross sections, lab-frame speed distributions, and angular distributions associated with the CD 3 products of the H + CD 4 (ν ) 0) f CD 3 + HD reaction at collision energies ranging from 0.5 to 3.0 eV. Of the potential energy surfaces (PES) we explored, the direct dynamics calculations using the B3LYP/6-31G** density functional theory PES provide the best agreement with the experimental measurements. This agreement is likely due to the better overall description that B3LYP provides for geometries well removed from the minimum energy path, even though its barrier height is low by ∼0.2 eV. In contrast to previous theoretical calculations, the angular distributions on this surface show behavior associated with a stripping mechanism, even at collision energies only ∼0.1 eV above the reaction barrier. Other potential energy surfaces, which include an analytical potential energy surface from Espinosa-García and a direct dynamics calculation based on the MSINDO semiempirical Hamiltonian, are less accurate and predict more rebound dynamics at these energies than is observed. Reparametrization of the MSINDO surface, though yielding better agreement with the experiment, is not sufficient to capture the observed dynamics. The differences between these surfaces are interpreted using an analysis of the opacity functions, where we find that the wider cone of acceptance on the B3LYP surface plays a crucial role in determining the integral cross sections and angular distributions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

Camden

Bechtel

et al. 2005

J. Phys. Chem. A

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“…However, for the similar H + CD 4 f CD 3 + HD ground-state reaction, Zare and co-workers [42][43][44] find that the CD 3 products are sideways/backward scattered, The distributions are normalized so that the area under the common levels is the same. P1, H-abstraction, channel 1, leads to the CD 3 + H2 products; P2, D-abstraction, channel 2, leads to the CHD2 + HD products.…”

Section: Product Energy Partitionmentioning

confidence: 99%

Quasi-Classical Trajectory Calculations Analyzing the Dynamics of the C−H Stretch Mode Excitation in the H + CHD₃ Reaction

Espinosa‐García

2007

J. Phys. Chem. A

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A state-to-state dynamics study was performed at a collision energy of 1.53 eV to analyze the effect of the C-H stretch mode excitation on the dynamics of the gas-phase H+CHD3 reaction, which can evolve along two channels, H-abstraction, CD3+H2, and D-abstraction, CHD2+HD. Quasi-classical trajectory calculations were performed on an analytical potential energy surface constructed previously by our group. First, strong coupling between different vibrational modes in the entry channel was observed; i.e., the reaction is non-adiabatic. Second, we found that the C-H stretch mode excitation has little influence on the product rotational distributions for both channels, and on the vibrational distribution for the CD3+H2 channel. However, it has significant influence on the product vibrational distribution for the CHD2+HD channel, where the C-H stretch excitation is maintained in the products, i.e., the reaction shows mode selectivity, reproducing the experimental evidence. Third, the C-H stretch excitation by one quantum increases the reactivity of the vibrational ground-state, in agreement with experiment. Fourth, the state-to-state angular distributions of the CD3 and CHD2 products are reported, finding that for the reactant ground-state the products are practically sideways, whereas the C-H excitation yields a more forward scattering.

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“…In addition, the cross-section is small even in the case of high collision energies [1]. Therefore, only a few experimental dynamics studies are available [1][2][3][4][5][6]. The first experimental study on the HD product energy distributions and the absolute cross-section for the H þ CD 4 !…”

Section: Introductionmentioning

confidence: 98%

Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄

Lü

Kuang

et al. 2011

Int J of Quantum Chemistry

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ABSTRACT:The mechanism and dynamics of the H þ CD 4 ! CD 3 þ HD (I) and H þ CH 4 ! CH 3 þ H 2 (II) reactions have been investigated by electronic structure methods. The minimum-energy path and vibrational frequencies along the intrinsic reaction coordinate are calculated at MP2/cc-pVDZ level. Energy distributions of the products are also obtained by the direct classical trajectory calculations at the MP2/ cc-pVDZ level. It is found that most of the available energy appears as product translational energy, and very little of the available energy is partitioned into internal excitation of the HD (H 2 ) product for reaction I (II), which is in agreement with the experimental evidence. The results indicate that the experimental results could be reproduced by the direct MP2 molecular dynamics calculations. The rotational state distributions of the products show the HD (H 2 ) products are formed with lower rotational quantum numbers than the CD 3 (CH 3 ) products.

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Dynamics of the Simplest Reaction of a Carbon Atom in a Tetrahedral Environment

Cited by 39 publications

References 28 publications

H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

Quasi-Classical Trajectory Calculations Analyzing the Dynamics of the C−H Stretch Mode Excitation in the H + CHD₃ Reaction

Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄

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Dynamics of the Simplest Reaction of a Carbon Atom in a Tetrahedral Environment

Cited by 39 publications

References 28 publications

H + CD4 Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

H + CD4 Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

Quasi-Classical Trajectory Calculations Analyzing the Dynamics of the C−H Stretch Mode Excitation in the H + CHD3 Reaction

Direct MP2 molecular dynamics studies of H atom reaction with CD4 and CH4

Contact Info

Product

Resources

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H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

H + CD₄ Abstraction Reaction Dynamics: Excitation Function and Angular Distributions

Quasi-Classical Trajectory Calculations Analyzing the Dynamics of the C−H Stretch Mode Excitation in the H + CHD₃ Reaction

Direct MP2 molecular dynamics studies of H atom reaction with CD₄ and CH₄