Coupled-channel statistical theory of the ()+ and ()+ insertion reactions

Rackham, Edward J.; Huarte-Larrañaga, Fermı́n; Manolopoulos, David E.

doi:10.1016/s0009-2614(01)00707-2

Cited by 187 publications

(291 citation statements)

References 18 publications

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“…Based on explicit close-coupling calculations, Honvault et al 228 reported a value of 4.15 × 10 −10 cm 3 s −1 for the conversion of ortho-H 2 ( j = 1) to para-H 2 ( j = 0) at 10 K, indicating high efficiency for the hydrogen atom exchange that drives the process. Similar calculations of D + + H 2 → HD + H + reaction by González-Lezana et al 229 using both quantum CC and the SQ approach developed by Rackham et al 230 predicted a rate coefficient value of (1.6-2.0) × 10 −9 cm 3 s −1 in the 10-100 K range. Lara et al 231 recently extended these calculations to the ultracold regime and found a nearly temperature independent value of ∼2.0 × 10 −9 cm 3 s −1 below 10 −4 K. Indeed, the rate coefficient value remained within an order of magnitude in the temperature range 10 −8 -100 K spanning 10 orders of magnitude, a value also accurately predicted by the Langevin model.…”

Section: E Field-free Reactive Scattering Calculationsmentioning

confidence: 67%

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

Balakrishnan

2016

The Journal of Chemical Physics

280

271

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Ultracold molecules offer unprecedented opportunities for the controlled interrogation of molecular events, including chemical reactivity in the ultimate quantum regime. The proliferation of methods to create, cool, and confine them has allowed the investigation of a diverse array of molecular systems and chemical reactions at temperatures where only a single partial wave contributes. Here we present a brief account of recent progress on the experimental and theoretical fronts on cold and ultracold molecules and the opportunities and challenges they provide for a fundamental understanding of bimolecular chemical reaction dynamics. Published by AIP Publishing. [http://dx

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Section: E Field-free Reactive Scattering Calculationsmentioning

confidence: 67%

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

Balakrishnan

2016

The Journal of Chemical Physics

280

271

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“…On average, the same P re describes the ultracold and the Langevin regimes. We have found a link between P re and the statistical factor of the statistical approach to reactions [23]. Apart from physical insight, our analysis provides ways to estimate the parameter y, which characterizes the experimental ultracold behavior, using ab initio reaction dynamics at much higher energies, where such methodology is assumed to be quantitative.…”

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confidence: 82%

“…Since the PES is characterized by a deep well or complex (≈4.5 eV), as illustrated in Fig. 1, rigorous statistical models [23,24] have been applied to this reaction and isotopic variants in the low and thermal energy regimes [20,[24][25][26][27] in good agreement with accurate …”

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confidence: 87%

Beyond universality: Parametrizing ultracold complex-mediated reactions using statistical assumptions

et al. 2015

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We have calculated accurate quantum reactive and elastic cross sections for the prototypical barrierless reaction D + + H 2 (v = 0, j = 0) using a modified hyperspherical scattering method. The considered kinetic energy ranges from the ultracold to the Langevin regimes. A reaction rate coefficient practically constant in no less than eight orders of magnitude is obtained. The availability of accurate results for this system allows one to test the quantum theory by Jachymski et al. [K. Jachymski, M. Krych, P. S. Julienne, and Z. Idziaszek, Phys. Rev. Lett. 110, 213202 (2013)] in a nonuniversal case. The short-range reaction probability is rationalized using statistical model assumptions and related to a statistical factor. This provides a means to estimate one of the parameters that characterizes ultracold processes from first principles. The increasing availability of cold and ultracold samples of atoms and molecules has sprung great interest in chemical reactions at very low temperatures [1][2][3][4][5]. Although new experimental approaches [5] appear highly promising, advances in the field are hampered by technical problems in producing most molecules at low temperatures and high enough densities. In contrast to neutral species, ions can be easily trapped and cooled. The technology of Coulomb crystals in radiofrequency ion traps [6] and the possibility of combining them with traps for neutrals or with slow molecular beams [7,8] promise great progress in the analysis of ion-neutral reactions in the near future.Theoretical simulations employing standard ab initio approaches are not feasible for most of the systems thus far considered. For heavy systems (more convenient experimentally) there are no potential energy surfaces (PESs) accurate enough to describe processes near thresholds. Additionally, most of exact dynamical treatments face insurmountable problems in such regimes. However, in contrast to short-range (SR) chemical interactions, those occurring at long range (LR) can be more easily calculated. Moreover, theoretical approaches based only on the knowledge of the LR part of the PES have been able to describe recent experimental findings nearly quantitatively [1,9]. Indeed, processes at very low collision energies favor LR interactions, leading to the idea of universality in extreme cases [10]: the result of the collision depends exclusively on the LR behavior and not on the details of the PES. In this regard, recently proposed LR parametrization procedures [9,[11][12][13] Fitting experimental data, these models are able to predict nonmeasured values providing some insight into the underlying interactions. In particular, the approach by Jachymski et al., based on multichannel quantum-defect theory (MQDT), provides analytical expressions which can be easily compared with experimental data [9,14,15]. The model has been recently applied to a variety of systems [9,16,17]. In particular, for the Penning ionization of Ar by He( 3 S) [5], the rate coefficients have been fitted in a wide range of collision ener...

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“…Thus, for instance, most of the information inferred from Rydberg H-atom time-offlight spectroscopic measurements [27][28][29] have been successfully reproduced 30,31 by means of a statistical quantum mechanical (SQM) method. 32,33 Different alternative approaches based on the assumption of the formation of an intermediate complex with a long enough lifetime before its fragmentation proved adequate to describe the dynamics of the process. [34][35][36][37][38][39] Changes of the mechanisms governing the reaction as a function on the collision energy regime have been, however, reported since the pioneering investigations on the H + 3 system.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

González‐Lezana

Honvault

Scribano

2013

The Journal of Chemical Physics

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The D + +H 2 (v = 0, j = 0, 1) → HD+H + reaction has been investigated at the low energy regime by means of a statistical quantum mechanical (SQM) method. Reaction probabilities and integral cross sections (ICSs) between a collisional energy of 10 −4 eV and 0.1 eV have been calculated and compared with previously reported results of a time independent quantum mechanical (TIQM) approach. The TIQM results exhibit a dense profile with numerous narrow resonances down to E c ∼ 10 −2 eV and for the case of H 2 (v = 0, j = 0) a prominent peak is found at ∼2.5 × 10 −4 eV. The analysis at the state-to-state level reveals that this feature is originated in those processes which yield the formation of rotationally excited HD(v = 0, j > 0). The statistical predictions reproduce reasonably well the overall behaviour of the TIQM ICSs at the larger energy range (E c ≥ 10 −3 eV). Thermal rate constants are in qualitative agreement for the whole range of temperatures investigated in this work, 10-100 K, although the SQM values remain above the TIQM results for both initial H 2 rotational states, j = 0 and 1. The enlargement of the asymptotic region for the statistical approach is crucial for a proper description at low energies. In particular, we find that the SQM method leads to rate coefficients in terms of the energy in perfect agreement with previously reported measurements if the maximum distance at which the calculation is performed increases noticeably with respect to the value employed to reproduce the TIQM results. © 2013 AIP Publishing LLC.

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Coupled-channel statistical theory of the ()+ and ()+ insertion reactions

Cited by 187 publications

References 18 publications

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

Beyond universality: Parametrizing ultracold complex-mediated reactions using statistical assumptions

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

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