Communication: Vibrational relaxation of CO(1Σ) in collision with Ar(1<i>S</i>) at temperatures relevant to the hypersonic flight regime

Denis-Alpizar, Otoniel; Bemish, Raymond J.; Meuwly, Markus

doi:10.1063/1.4978498

Cited by 8 publications

(6 citation statements)

References 35 publications

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“…For nonreactive collisions (e.g., Ar+CO), PESs are computed only for the reactant channel. However, in order to allow chemical reactions to be described, bonds need to be broken and formed.…”

Section: Computational Modelsmentioning

confidence: 99%

“…For example, it was shown for N 2 +N and N 2 +N 2 that, using the Millikan–White vibrational relaxation model, the TT v model predicts a much faster N 2 dissociation for T ≤ 20 000 K than that obtained with direct molecular simulations, whereas for T = 30000 K, the two models agree . Additional work on vibrational relaxation , shows that there is a clear difference between the modified Millikan and White model for vibrational relaxation and what is expected from high fidelity quantum mechanical or quasiclassical trajectory simulations, by up to 1 order of magnitude. Since these rates affect the major chemical species in the flow, they will at the largest scale even influence the aerodynamic properties.…”

Section: Introductionmentioning

confidence: 97%

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Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

2020

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The determination of thermal and vibrational relaxation rates of triatomic systems suitable for application in hypersonic model calculations is discussed. For this, potential energy surfaces for ground and electronically excited state species need to be computed and represented with high accuracy, and quasiclassical or quantum nuclear dynamics simulations provide the basis for determining the relevant rates. These include thermal reaction rates, state-to-state cross sections, and vibrational relaxation rates. For exemplary systems (i.e., [NNO], [NOO], and [CNO]), all individual steps are described, and a literature overview for them is provided. Finally, as some of these quantities involve considerable computational expense, for the example of state-to-state cross sections, the construction of an efficient model based on neural networks is discussed. All such data is required and being used in more coarse-grained computational fluid dynamics simulations.

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Section: Computational Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

2020

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“…Stratified Sampling: Reactive molecular dynamics simulations were performed using stratified sampling for b. 34,35 For the stratified sampling all trajectories were grouped in nonoverlapping intervals of b with a weight…”

Section: Ms-armdmentioning

confidence: 99%

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Sweeny

Pan

Kassem

et al. 2020

Phys. Chem. Chem. Phys.

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The kinetics of MgO + + CH 4 was studied experimentally using the variable ion source, temperature adjustable selected ion flow tube (VISTA-SIFT) apparatus from 300 − 600 K and computationally by running and analyzing reactive atomistic simulations. Rate coefficients and product branching fractions were determined as a function of temperature. The reaction proceeded with a rate of k = 5.9 ± 1.5 × 10 −10 (T /300 K) −0.5±0.2 cm 3 s −1 . MgOH + was the dominant product at all temperatures, but Mg + , the co-product of oxygen-atom transfer to form methanol, was observed with a product branching fraction of 0.08 ± 0.03(T /300 K) −0.8±0.7 . Reactive molecular dynamics simulations using a reactive force field, as well as a neural network trained on thousands of structures yield rate coefficients about one order of magnitude lower.This underestimation of the rates is traced back to the multireference character of the transition state [MgOCH 4 ] + . Statistical modeling of the temperature-dependent kinetics provides further insight into the reactive potential surface. The rate limiting step was found to be consistent with a four-centered activation of the C-H bond, consistent with previous calculations. The product branching was modeled as a competition between dissociation of an insertion intermediate directly after the ratelimiting transition state, and traversing a transition state corresponding to a methyl migration leading to a Mg-CH 3 OH + complex, though only if this transition state is stabilized significantly relative to the dissociated MgOH + + CH 3 product channel.An alternative non-statistical mechanism is discussed, whereby a post-transition state bifurcation in the potential surface could allow the reaction to proceed directly from the four-centered TS to the Mg-CH 3 OH + complex thereby allowing a more robust competition between the product channels. a) rvborgmailbox@us.af.mil b) m.meuwly@unibas.ch

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“…The same procedure was previously followed for NO 2 , ArN + 2 , N 2 O and ArCO. [31][32][33][34] Finally, the global PES for an electronic state is constructed by smoothly connecting the three PESs 35,36 for channels I to III using a switching function (w i (r)) according to…”

Section: A the Potential Energy Surfacesmentioning

confidence: 99%

The C(3P) + NO(X2Π) → O(3P) + CN(X2Σ+), N(2D)/N(4S) + CO(X1Σ+) reaction: Rates, branching ratios, and final states from 15 K to 20 000 K

Koner

Bemish

Meuwly

2018

The Journal of Chemical Physics

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The C + NO collision system is of interest in the area of high-temperature combustion and atmospheric chemistry. In this work, full dimensional potential energy surfaces for the A',A″, and A″ electronic states of the [CNO] system have been constructed following a reproducing kernel Hilbert space approach. For this purpose, more than 50 000 energies are calculated at the MRCI+Q/aug-cc-pVTZ level of theory. The dynamical simulations for the C(P) + NO(XΠ) → O(P) + CN(XΣ), N(D)/N(S) + CO(XΣ) reactive collisions are carried out on the newly generated surfaces using the quasiclassical trajectory (QCT) calculation method to obtain reaction probabilities, rate coefficients, and the distribution of product states. Preliminary quantum calculations are also carried out on the surfaces to obtain the reaction probabilities and compared with QCT results. The effect of nonadiabatic transitions on the dynamics for this title reaction is explored within the Landau-Zener framework. QCT simulations have been performed to simulate molecular beam experiment for the title reaction at 0.06 and 0.23 eV of relative collision energies. Results obtained from theoretical calculations are in good agreement with the available experimental as well as theoretical data reported in the literature. Finally, the reaction is studied at temperatures that are not practically achievable in the laboratory environment to provide insight into the reaction dynamics at temperatures relevant to hypersonic flight.

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Communication: Vibrational relaxation of CO(1Σ) in collision with Ar(1S) at temperatures relevant to the hypersonic flight regime

Cited by 8 publications

References 35 publications

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

The C(3P) + NO(X2Π) → O(3P) + CN(X2Σ+), N(2D)/N(4S) + CO(X1Σ+) reaction: Rates, branching ratios, and final states from 15 K to 20 000 K

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Communication: Vibrational relaxation of CO(1Σ) in collision with Ar(1S) at temperatures relevant to the hypersonic flight regime

Cited by 8 publications

References 35 publications

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

Thermal activation of methane by MgO+: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

The C(3P) + NO(X2Π) → O(3P) + CN(X2Σ+), N(2D)/N(4S) + CO(X1Σ+) reaction: Rates, branching ratios, and final states from 15 K to 20 000 K

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Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling