Current Status of Transition-State Theory

Truhlar, Donald G.; Garrett, Bruce C.; Klippenstein, Stephen J.

doi:10.1021/jp953748q

Cited by 1,980 publications

(1,451 citation statements)

References 785 publications

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“…Of course, the significance of adiabatic barriers in determining reaction rate constants has been explored exhaustively. 62 In some cases, the cumulative reaction probability, which is proportional to the microcanonical rate constant, exhibits visible steps as the energy passes through the bottleneck energies. 20,63 One also expects the quantized bottlenecks will influence state-to-state scattering attributes, but in a more complicated manner.…”

Section: Quantum Reaction Dynamicsmentioning

confidence: 99%

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

Chao

Harich

Dai

et al. 2002

The Journal of Chemical Physics

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We present the results of a joint experimental and theoretical investigation of the reaction dynamics of the HϩHD→DϩH 2 chemical reaction. The experiment was performed using a crossed molecular beam apparatus that employed the Rydberg-atom time-of-flight detection scheme for the product D atom. The photolysis of a HI precursor molecule produced a beam source of hot H atoms, which, when crossed with a cold HD beam, yielded two well-defined center-of-mass collision energies, E C ϭ0.498 and 1.200 eV. The resolution of the experiment was sufficient to allow the measurement of the rovibrationally state-resolved differential cross section from the ground state of the HD reagent. The reaction was modeled theoretically using a converged coupled channel scattering calculation employing the BKMP2 potential energy surface: The S matrix was computed on a grid of 56 energies in the range E C ϭ0.245-1.551 eV. It is found that the experimental and theoretical state-to-state differential cross sections are in quantitative agreement at the two experimental energies. The geometric phase, which was not included in the calculation, is apparently not required at the energies considered. The spin statistics for the two identical protons is observed to have a dramatic effect on the rotational distribution of H 2 products, giving rise to a saw-toothed distribution with odd-jЈϾeven-jЈ. The differential cross section for several of the product states exhibited a dramatic forward peak that may be the signature of trapped quantum states near the saddle point. A detailed analysis of the reaction attributes is presented based on the energy dependence of the computed S matrix.

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Section: Quantum Reaction Dynamicsmentioning

confidence: 99%

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

Chao

Harich

Dai

et al. 2002

The Journal of Chemical Physics

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“…In the present work, we performed dual-level (X//Y) direct dynamics calculations [13][14][15] to investigate the kinetic nature of the title reaction. The required potential energy surface (PES) information for the kinetic calculations was obtained directly from the electronic structure calculations, in which the M06-2X density functional method 16 was used to optimize all the stationary points on the PES, and multilevel MCG3-MPWB method 17 was used to calculate the highlevel single-point energies at the M06-2X geometries.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies on Mechanism and Kinetics of the Hydrogen-Abstraction Reaction of CF₃CH₂CHO with OH Radicals

Ci¹,

Yu²,

Wan³

et al. 2011

Bulletin of the Korean Chemical Society

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The hydrogen abstraction reaction of CF 3 CH 2 CHO + OH has been studied theoretically by dual-level direct dynamics method. Two stable conformers, trans-and cis-CF 3 CH 2 CHO, have been located, and there are four distinct OH hydrogen-abstraction channels from t-CF 3 CH 2 CHO and two channels from c-CF 3 CH 2 CHO. The required potential energy surface information for the kinetic calculation was obtained at the MCG3-MPWB// M06-2X/aug-cc-pVDZ level. The rate constants, which were calculated using improved canonical transitionstate theory with small-curvature tunneling correction (ICVT/SCT) were fitted by a four-parameter Arrhenius equation. It is shown that the reaction proceeds predominantly via the H-abstraction from the -CHO group over the temperature range 200-2000 K. The calculated rate constants were in good agreement with the experimental data between 263 and 358 K.

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“…This method has been widely validated. 18,19 Finally, in category III is an approximate quantum mechanical method in which the adiabatic bend (QM/AB) approximation [20][21][22] is used to reduce the dimensionality and the J-shifting 23 approximation is used to obtain approximate results (QM/AB-JS) for higher J in terms of those for J = 0.…”

Section: Introductionmentioning

confidence: 99%

Thermal and State-Selected Rate Coefficients for the O(³P) + HCl Reaction and New Calculations of the Barrier Height and Width

et al. 2001

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This paper compares several approximate methods for calculating rate coefficients for the O( 3 P) + HCl reaction to presumably more accurate quantum mechanical calculations based on applying the J-shifting approximation (QM/JS) to an accurate cumulative reaction probability for J = 0.All calculations for this work employ the recent S4 potential energy surface, which presents a number of challenges for the approximate methods. The O + HCl reaction also poses a significant challenge to computational dynamics because of the heavy-light-heavy mass combination and the broad noncollinear reaction path. The approximate methods for calculating 2 the thermal rate coefficient that are examined in this article are quasiclassical trajectories (QCT), conventional transition state theory (TST), variational transition state theory employing the improved canonical variational theory (ICVT), ICVT with the microcanonical optimized multidimensional tunneling correction (ICVT/µOMT), and reduced dimensionality quantum mechanical calculations based on adiabatic bend and J-shifting (QM/AB-JS) approximations. It is seen that QCT, TST, and ICVT rate coefficients agree with each other within a factor of 2.7 at 250 K and 1.6 at l000 K, whereas inclusion of tunneling by the ICVT/µOMT, QM/AB-JS, or QM/JS methods increases the rate coefficients considerably. However, the ICVT/µOMT and QM/AB-JS methods yield significantly lower rate coefficients than the QM/JS calculations, especially at lower temperatures. We also report and discuss calculations for the state-selected reaction of O( 3 P) with HCl in the first excited vibrational state. In addition to the dynamics calculations, we report new electronic structure calculations by the multi-coefficient Gaussian-3 (MCG3) method that indicate that one possible source of disagreement between the QM/JS rate coefficients and experiment is that the barrier on the S4 surface may be too narrow.

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Current Status of Transition-State Theory

Cited by 1,980 publications

References 785 publications

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

Theoretical Studies on Mechanism and Kinetics of the Hydrogen-Abstraction Reaction of CF₃CH₂CHO with OH Radicals

Thermal and State-Selected Rate Coefficients for the O(³P) + HCl Reaction and New Calculations of the Barrier Height and Width

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Current Status of Transition-State Theory

Cited by 1,980 publications

References 785 publications

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics

Theoretical Studies on Mechanism and Kinetics of the Hydrogen-Abstraction Reaction of CF3CH2CHO with OH Radicals

Thermal and State-Selected Rate Coefficients for the O(3P) + HCl Reaction and New Calculations of the Barrier Height and Width

Contact Info

Product

Resources

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Theoretical Studies on Mechanism and Kinetics of the Hydrogen-Abstraction Reaction of CF₃CH₂CHO with OH Radicals

Thermal and State-Selected Rate Coefficients for the O(³P) + HCl Reaction and New Calculations of the Barrier Height and Width