Quasi-classical trajectory study of the dynamics of the Cl + CH4→ HCl + CH3 reaction

Greaves, Stuart J.; Rose, RA; Abou‐Chahine, Fawzi; Glowacki, David R.; Troya, Diego; Orr-Ewing, Andrew J.

doi:10.1039/c0cp02694h

Cited by 24 publications

(36 citation statements)

References 57 publications

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“…(Note that a recent study 28 reported a classical barrier height of 2385 cm −1 obtained at CCSD(T)/CBS//CCSD(T)/aug-cc-pVTZ, which value is slightly smaller than our more rigorous CCSD(T)/CBS value of 2440 cm −1 and much smaller than our benchmark value of 2670 cm −1 . The difference in the CBS value is due to the fact that Ref.…”

Section: The CL + Ch 4 → Hcl + Ch 3 Reactioncontrasting

confidence: 61%

“…Also in that year, Troya and Weiss 12 reported a specific reaction parameter (SRP) semi-empirical Hamiltonian (SRP-MSINDO) for the Cl + CH 4 reaction allowing efficient on-the-fly computation of the PES. In 2011 Greaves et al 28 showed that another semi-empirical Hamiltonian (SRP-AM1), which was previously optimized for the Cl + ethane reaction, can be used for the title reaction.…”

Section: Introductionmentioning

confidence: 99%

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Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Czakó

Bowman

2012

The Journal of Chemical Physics

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We report a high-quality, ab initio, full-dimensional global potential energy surface (PES) for the Cl((2)P, (2)P(3/2)) + CH(4) reaction, which describes both the abstraction (HCl + CH(3)) and substitution (H + CH(3)Cl) channels. The analytical PES is a least-squares fit, using a basis of permutationally invariant polynomials, to roughly 16,000 ab initio energy points, obtained by an efficient composite method, including counterpoise and spin-orbit corrections for the entrance channel. This composite method is shown to provide accuracy almost equal to all-electron CCSD(T)/aug-cc-pCVQZ results, but at much lower computational cost. Details of the PES, as well as additional high-level benchmark characterization of structures and energetics are reported. The PES has classical barrier heights of 2650 and 15,060 cm(-1) (relative to Cl((2)P(3/2)) + CH(4)(eq)), respectively, for the abstraction and substitution reactions, in good agreement with the corresponding new computed benchmark values, 2670 and 14,720 cm(-1). The PES also accurately describes the potential wells in the entrance and exit channels for the abstraction reaction. Quasiclassical trajectory calculations using the PES show that (a) the inclusion of the spin-orbit corrections in the PES decreases the cross sections by a factor of 1.5-2.5 at low collision energies (E(coll)); (b) at E(coll) ≈ 13,000 cm(-1) the substitution channel opens and the H/HCl ratio increases rapidly with E(coll); (c) the maximum impact parameter (b(max)) for the abstraction reaction is ~6 bohr; whereas b(max) is only ~2 bohr for the substitution; (d) the HCl and CH(3) products are mainly in the vibrational ground state even at very high E(coll); and (e) the HCl rotational distributions are cold, in excellent agreement with experiment at E(coll) = 1280 cm(-1).

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Section: The CL + Ch 4 → Hcl + Ch 3 Reactioncontrasting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Czakó

Bowman

2012

The Journal of Chemical Physics

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“…For example, Troya and coworkers used a full-dimensional semi-empirical PES to perform quasi-classicaltrajectory (QCT) calculations. [38][39] The first global pre-calculated ab initio PES used in QCT calculations was reported by Castillo et al 40 Their approach used QCISD(T)/aug-cc-pVTZ//QCISD/cc-pVTZ calculations to determine the energies of the separated reactants and products and those of the preand post-reaction complexes. The other regions of the PES were calculated using the interpolation algorithms of Collins and co-workers.…”

Section: Introductionmentioning

confidence: 99%

“…Fully dimensional on-the-fly classical dynamics calculations were carried out for the CH4 + Cl reaction using a semi-empirical model Hamiltonian by Troya et al 38,45 and using the Hartree-Fock /6-31G level of theory by Rudić et al 46 A similar approach was adopted by Greaves et al who investigated the transferability of model Hamiltonians between related reactions. 39 The purpose of the current study is to test the EVB description of a PES generated from high level ab initio electronic structure calculations. The EVB fit to obtain a global PES requires fewer ab initio points than the alternative PES fitting methods described above.…”

Section: Introductionmentioning

confidence: 99%

Empirical Valence Bond Theory Studies of the CH₄ + Cl → CH₃ + HCl Reaction

et al. 2015

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We report a theoretical investigation of the CH4 + Cl hydrogen abstraction reaction in the framework of empirical valence bond (EVB) theory. The main purpose of this study is to benchmark the EVB method against previous experimental and theoretical work. Analytical potential energy surfaces for the reaction have been developed on which quasi-classical trajectory calculations were carried out.The surfaces agree well with ab initio calculations at stationary points along the reaction path and dynamically relevant regions outside the reaction path. The analysis of dynamical data obtained using the EVB method, such as vibrational, rotational and angular distribution functions, shows that this method compares well to both experimental measurements and higher-level theoretical calculations, with the additional benefit of low computational cost.

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“…In many cases, the bonds that do not break retain their initial excitation and are, to a first approximation, simply spectators in the reaction. 2,3,[8][9][10] This well-characterized behavior of the methane isotopologues, as well as the importance of reactions of methane with Cl in the upper atmosphere, 11 have motivated a large set of experimental 1-5, 8-10, 12-20 and theoretical [21][22][23][24][25][26][27] studies, placing reactions of methane among the most carefully studied of any polyatomic molecule. Against this backdrop, we investigate experimentally the energetics of the reaction of CH 3 D with Cl to make a careful comparison with theoretical calculations.…”

Section: Introductionmentioning

confidence: 99%

The influence of translational and vibrational energy on the reaction of Cl with CH3D

Berke

Volpa

Annesley

et al. 2013

The Journal of Chemical Physics

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The reaction of Cl atoms with CH3D proceeds either by abstraction of hydrogen to produce HCl + CH2D or by abstraction of deuterium to produce DCl + CH3. Using Cl atoms with different amounts of translational energy, produced by photolysis of Cl2 with 309, 355, or 416 nm light, reveals the influence of translational energy on the relative reaction probability for the two channels. These measurements give an estimate of the energy barrier for the reaction for comparison to theory and indicate that tunneling is the dominant reaction mechanism at low collision energies. Adding two quanta of C-H stretching vibration causes the reaction to proceed readily at all collision energies. Detecting the vibrational state of the CH2D product shows that vibrational energy initially in the surviving C-H bond appears as vibrational excitation of the product, an example of spectator behavior in the reaction. The reaction produces both stretch and stretch-bend excited products except at the lowest collision energy. A subtle variation in the reaction probability of the lowest energy rotational states with translational energy may reflect the presence of a van der Waals well in the entrance channel.

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Quasi-classical trajectory study of the dynamics of the Cl + CH4→ HCl + CH3 reaction

Abstract: We present an on-the-fly classical trajectory study of the Cl + CH4  HCl + CH3 reaction using a specific reaction parameter (SRP) AM1 Hamiltonian that was previously optimized for the Cl +

Cited by 24 publications

References 57 publications

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Empirical Valence Bond Theory Studies of the CH₄ + Cl → CH₃ + HCl Reaction

The influence of translational and vibrational energy on the reaction of Cl with CH3D

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Quasi-classical trajectory study of the dynamics of the Cl + CH4→ HCl + CH3 reaction

Abstract: We present an on-the-fly classical trajectory study of the Cl + CH4  HCl + CH3 reaction using a specific reaction parameter (SRP) AM1 Hamiltonian that was previously optimized for the Cl +

Cited by 24 publications

References 57 publications

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Accurate ab initio potential energy surface, thermochemistry, and dynamics of the Cl(2P, 2P3/2) + CH4 → HCl + CH3 and H + CH3Cl reactions

Empirical Valence Bond Theory Studies of the CH4 + Cl → CH3 + HCl Reaction

The influence of translational and vibrational energy on the reaction of Cl with CH3D

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Empirical Valence Bond Theory Studies of the CH₄ + Cl → CH₃ + HCl Reaction