Exploring the Multiple Reaction Pathways for the H + cyc-C<sub>3</sub>H<sub>6</sub> Reaction

Yu, Hua Gen; Muckerman, James T.

doi:10.1021/jp0458194

Cited by 34 publications

(81 citation statements)

References 35 publications

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“…The dissociation energy of 87.6 kcal/mol was found at MRCIþQ/CBS//CAS(10,10)/cc-pVDZ level (were CBS refers to an extrapolation from the aug-cc-pVDZ and aug-cc-VTZ basis sets), [52] which is close to our MRPT(6,4)/ CCD//CAS(6,4)/CCD value. Xia et al [22] report dissociation limits for CH 3 OH !…”

Section: Ohsupporting

confidence: 83%

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Oliveira¹,

Bauerfeldt²

2012

Int J of Quantum Chemistry

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Here, a new implementation for calculating canonical variational rate constants is introduced and tested against methanol dissociation rate constants and the (high pressure) radical recombination reaction, CH 3 þ OH ! CH 3 OH. Reaction paths are described at the CASSCF level, with energy corrections at MRMP2. Molecular properties for both stationary and non-stationary points along the reaction path are used for the calculation of rate constants. Different models for the low vibrational frequencies are discussed: harmonic oscillator and free rotor models. The CH 3 þ OH ! CH 3 OH recombination rate constants are determined from dissociation rate constants and equilibrium constants. Our calculated rate constants agree with previously reported data for these reactions, suggesting the good performance of our implemented code in calculating canonical variational rate constants. The rate expressions are suggested: as: k dis (T) ¼ 8.42 Â 10 þ16 Â e À96.18/RT and k rec (T) ¼ 2.05 Â 10 À10 Â (T/298) À0.24 Â e À0.30/RT , in units s À1 and cm 3 molecule À1 s À1 , respectively, and over the temperature range 300-2000 K, with activation energies in kcal/mol.

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Section: Ohsupporting

confidence: 83%

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Oliveira¹,

Bauerfeldt²

2012

Int J of Quantum Chemistry

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“…It was first tested on HOOH where its efficiency was established [157]. Yu has contracted the bend but not the stretch basis to compute energy levels for several molecules [159,160,194]. Lee and Light contracted both bend and stretch bases [161,162].…”

Section: Chmentioning

confidence: 99%

Variational quantum approaches for computing vibrational energies of polyatomic molecules

2008

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In this article we review state-of-the-art methods for computing vibrational energies of polyatomic molecules using quantum mechanical, variationally-based approaches. We illustrate the power of those methods by presenting applications to molecules with more than four atoms. This demonstrates the great progress that has been made in this field in the last decade in dealing with the exponential scaling with the number of vibrational degrees of freedom. In this review we present three methods that effectively obviate this bottleneck. The first important idea is the n-mode representation of the Hamiltonian and notably the potential. The potential (and other functions) are represented as a sum of terms that depend on a subset of the coordinates. This makes it possible to compute matrix elements, form a Hamiltonian matrix, and compute its eigenvalues and eigenfunctions. Another approach takes advantage of this multimode representation and represents the terms as sum of products. It then exploits the powerful multiconfiguration Hartree time dependent method to solve the time-dependent Schrödinger equation and extract the eigenvalue spectrum. The third approach we present uses contracted basis functions in conjunction with a Lanczos eigensolver. Matrix vector products are done without transforming to a direct-product grid. The usefulness of these methods is demonstrated for several example molecules, e.g., methane, methanol and the Zundel cation.2

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“…One caution in developing predictive ability for the bimolecular reactions is, however, that there is the implicit assumption that the reaction proceeds via an initial addition to form the corresponding radical intermediate. Though this assumption is expected to be quite good for the systems studied here, for reactions such as O( 1 D) + methane it has been shown that the reaction proceeds through both direct and the longlived intermediate pathways; 34 then studies of the unimolecular dissociation of the intermediate would only probe the latter pathway for the bimolecular reaction.…”

mentioning

confidence: 97%

A Study of the Unimolecular Dissociation of the 2-Buten-2-yl Radical via the 193 nm Photodissociation of 2-Chloro-2-butene

et al. 2005

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This work investigates the unimolecular dissociation of the 2-buten-2-yl radical. This radical has three potentially competing reaction pathways: C-C fission to form CH 3 + propyne, C-H fission to form H + 1,2-butadiene, and C-H fission to produce H + 2-butyne. The experiments were designed to probe the branching to the three unimolecular dissociation pathways of the radical and to test theoretical predictions of the relevant dissociation barriers. Our crossed laser-molecular beam studies show that 193 nm photolysis of 2-chloro-2-butene produces 2-buten-2-yl in the initial photolytic step. A minor C-Cl bond fission channel forms electronically excited 2-buten-2-yl radicals and the dominant C-Cl bond fission channel produces groundstate 2-buten-2-yl radicals with a range of internal energies that spans the barriers to dissociation of the radical. Detection of the stable 2-buten-2-yl radicals allows a determination of the translational, and therefore internal, energy that marks the onset of dissociation of the radical. The experimental determination of the lowest-energy dissociation barrier gave 31 ( 2 kcal/mol, in agreement with the 32.8 ( 2 kcal/mol barrier to C-C fission at the G3//B3LYP level of theory. Our experiments detected products of all three dissociation channels of unstable 2-buten-2-yl as well as a competing HCl elimination channel in the photolysis of 2-chloro-2-butene. The results allow us to benchmark electronic structure calculations on the unimolecular dissociation reactions of the 2-buten-2-yl radical as well as the CH 3 + propyne and H + 1,2-butadiene bimolecular reactions. They also allow us to critique prior experimental work on the H + 1,2-butadiene reaction.

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Exploring the Multiple Reaction Pathways for the H + cyc-C₃H₆ Reaction

Cited by 34 publications

References 35 publications

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Variational quantum approaches for computing vibrational energies of polyatomic molecules

A Study of the Unimolecular Dissociation of the 2-Buten-2-yl Radical via the 193 nm Photodissociation of 2-Chloro-2-butene

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Exploring the Multiple Reaction Pathways for the H + cyc-C3H6 Reaction

Cited by 34 publications

References 35 publications

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH3OH = CH3 + OH

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH3OH = CH3 + OH

Variational quantum approaches for computing vibrational energies of polyatomic molecules

A Study of the Unimolecular Dissociation of the 2-Buten-2-yl Radical via the 193 nm Photodissociation of 2-Chloro-2-butene

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Product

Resources

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Exploring the Multiple Reaction Pathways for the H + cyc-C₃H₆ Reaction

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH