Depression of reactivity by the collision energy in the single barrier H + CD
            <sub>4</sub>
             → HD + CD
            <sub>3</sub>
            reaction

Zhang, Weiqing; Zhou, Yong; Wu, Guorong; Lu, Yunpeng; Pan, Huilin; Fu, Bina; Shuai, Quan; Liu, Lan; Shu, Liu; Zhang, Liling; Jiang, Bo; Dai, Dongxu; Lee, Soo-Ying; Xie, Zhen; Braams, Bastiaan J.; Bowman, Joel M.; Collins, Michael A.; Zhang, Dong H.; Yang, Xueming

doi:10.1073/pnas.1006910107

Cited by 108 publications

(72 citation statements)

References 34 publications

(26 reference statements)

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“…It is interesting to find that the n 1 ¼ 1 abstraction ICSs increase up to a E coll of B40 kcal mol À 1 and then a slight decay is seen, because the faster reactants have less time to interact with each other. This depression of reactivity with the increase of E coll was also found in the H þ CD 4 -HD þ CD 3 reaction 19 . Figure 2 also shows the ICSs for the configuration-retaining substitution.…”

Section: Reaction Dynamics Simulationsmentioning

confidence: 62%

“…Figure 2 also shows the ICSs for the configuration-retaining substitution. These ICSs are much smaller than those of the inversion mechanism (1.1% and 2.3% at E coll ¼ 60 kcal mol À 1 for n ¼ 0 and n 1 ¼ 1, respectively), but the absolute ICSs are not negligible since, for example, the H þ CD 4 reaction has similar small ICSs 19 . For F À þ CH 3 Cl(n ¼ 0), the configuration-retaining pathway opens at a E coll of B10 kcal mol À 1 , the ICSs rise up to E coll ¼ B30 kcal mol À 1 , then decay and increase again around E coll ¼ 40 À 50 kcal mol À 1 .…”

Section: Reaction Dynamics Simulationsmentioning

confidence: 94%

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Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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Stereo-specific reaction mechanisms play a fundamental role in chemistry. The back-side attack inversion and front-side attack retention pathways of the bimolecular nucleophilic substitution (S N 2) reactions are the textbook examples for stereo-specific chemical processes. Here, we report an accurate global analytic potential energy surface (PES) for the F À þ CH 3 Cl S N 2 reaction, which describes both the back-side and front-side attack substitution pathways as well as the proton-abstraction channel. Moreover, reaction dynamics simulations on this surface reveal a novel double-inversion mechanism, in which an abstraction-induced inversion via a FH Á Á Á CH 2 Cl À transition state is followed by a second inversion via the usual [F Á Á Á CH 3 Á Á Á Cl] À saddle point, thereby opening a lower energy reaction path for retention than the front-side attack. Quasi-classical trajectory computations for the F À þ CH 3 Cl(n 1 ¼ 0, 1) reactions show that the front-side attack is a fast direct, whereas the double inversion is a slow indirect process.

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Section: Reaction Dynamics Simulationsmentioning

confidence: 62%

Section: Reaction Dynamics Simulationsmentioning

confidence: 94%

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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“…[2][3][4][5][6][7][8] It has also served as a benchmark for understanding bimolecular reaction dynamics involving polyatomic molecules. [9][10][11] Due to the involvement of light hydrogenic atoms, the reaction is intrinsically quantum mechanical. Quantum effects, such as tunneling and zero-point energy (ZPE), manifest not only in dynamics, but also in kinetics as well.…”

Section: Introductionmentioning

confidence: 99%

Rate coefficients and kinetic isotope effects of the X + CH4 → CH3 + HX (X = H, D, Mu) reactions from ring polymer molecular dynamics

Suleimanov

et al. 2013

The Journal of Chemical Physics

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The thermal rate coefficients and kinetic isotope effects have been calculated using ring polymer molecular dynamics (RPMD) for the prototypical reactions between methane and several hydrogen isotopes (H, D, and Mu). The excellent agreement with the theoretical rate coefficients of the H + CH 4 reaction obtained previously from a multiconfiguration time-dependent Hartree (MCTDH) calculation on the same potential energy surface provides strong evidence for the accuracy of the RPMD approach. These quantum mechanical rate coefficients are also in good agreement with the results obtained previously using the transition-state theory with semi-classical tunneling corrections for the H/D + CH 4 reaction reactions. However, it is shown that the RPMD rate coefficients for the ultralight Mu reaction with CH 4 are significantly smaller than the experimental data, presumably suggesting inaccuracies in the potential energy surface.Significant discrepancies between the RPMD and transition-state theory results have also been found for this challenging system.

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“…The deviation of the RD excitation functions from the FD ones also hints that one needs to be cautious when comparing experimentally measured cross sections with those from RD quantum scattering calculations, such as done in Ref. 52. Our overall conclusion from the classical mechanics studies is that the reduceddimensionality model provides results close to the full-dimensional one in some cases while in other cases significant deviations can be seen; the consequences of dimensionality reduction seem hard to predict.…”

Section: Discussionmentioning

confidence: 62%

Testing the Palma–Clary Reduced Dimensionality Model Using Classical Mechanics on the CH₄ + H → CH₃ + H₂ Reaction

2016

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KEYWORDS Reduced dimensionality quantum scattering, Palma-Clary Hamiltonian, reaction cross section, quasiclassical trajectory method, one-period averaging method.ABSTRACT Application of exact quantum scattering methods in theoretical reaction dynamics of bimolecular reactions is limited by the complexity of the equations of nuclear motion to be solved.Simplification is often achieved by reducing the number of degrees of freedom to be explicitly handled by freezing the less important spectator ones. The reaction cross sections obtained in reduced-dimensionality (RD) quantum scattering methods can be used in the calculation of rate coefficients, but their physical meaning is limited. The accurate test of the performance of a reduced-dimensionality method would be a comparison of the RD cross sections with those obtained in accurate full-dimensional (FD) calculations, which is not feasible due to the lack of complete full-dimensional results. However, classical mechanics allows one to perform reaction dynamics calculations using both the RD and the FD model. In this paper an RD vs. FD comparison is made for the 8-dimensional Palma-Clary model on the example of four isotopologs of the CH4 + H → CH3 + H2 reaction, which has 12 internal dimensions. In the Palma-Clary model the only restriction is that the methyl group is confined to maintain C3v symmetry. Both RD and FD 2 opacity and excitation functions as well as differential cross sections were calculated using the quasiclassical trajectory method. The initial reactant separation has been handled according to our one-period averaging, 1PA method [Nagy, T.;Vikár, A.; Lendvay, G. J. Chem. Phys. 2016, 144, 014104]. The RD and FD excitation functions were found to be close to each other for some isotopologs but in general, the RD reactivity parameters are lower than the FD ones beyond statistical error and for one of the isotopologs the deviation is significant. This indicates that the goodness of RD cross sections cannot be taken for granted.

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Depression of reactivity by the collision energy in the single barrier H + CD ₄ → HD + CD ₃ reaction

Cited by 108 publications

References 34 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Rate coefficients and kinetic isotope effects of the X + CH4 → CH3 + HX (X = H, D, Mu) reactions from ring polymer molecular dynamics

Testing the Palma–Clary Reduced Dimensionality Model Using Classical Mechanics on the CH₄ + H → CH₃ + H₂ Reaction

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Depression of reactivity by the collision energy in the single barrier H + CD 4 → HD + CD 3 reaction

Cited by 108 publications

References 34 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Rate coefficients and kinetic isotope effects of the X + CH4 → CH3 + HX (X = H, D, Mu) reactions from ring polymer molecular dynamics

Testing the Palma–Clary Reduced Dimensionality Model Using Classical Mechanics on the CH4 + H → CH3 + H2 Reaction

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Product

Resources

About

Depression of reactivity by the collision energy in the single barrier H + CD ₄ → HD + CD ₃ reaction

Testing the Palma–Clary Reduced Dimensionality Model Using Classical Mechanics on the CH₄ + H → CH₃ + H₂ Reaction