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Murakami T, Takahashi S, Kikuma Y, Takayanagi T. Theoretical Study of the Thermal Rate Coefficients of the H 3+ + C 2H 4 Reaction: Dynamics Study on a Full-Dimensional Potential Energy Surface. Molecules 2024; 29:2789. [PMID: 38930853 PMCID: PMC11206701 DOI: 10.3390/molecules29122789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 06/08/2024] [Accepted: 06/09/2024] [Indexed: 06/28/2024] Open
Abstract
Ion-molecular reactions play a significant role in molecular evolution within the interstellar medium. In this study, the entrance channel reaction, H3+ + C2H4 → H2 + C2H5+, was investigated using classical molecular dynamic (classical MD) and ring polymer molecular dynamic (RPMD) simulation techniques. We developed an analytical potential energy surface function with a permutationally invariant polynomial basis, specifically employing the monomial symmetrized approach. Our dynamic simulations reproduced the rate coefficient of 300 K for H3+ + C2H4 → H2 + C2H5+, aligning reasonably well with the values in the kinetic database commonly utilized in astrochemistry. The thermal rate coefficients obtained using both the classical MD and RPMD techniques exhibited an increase from 100 K to 300 K as the temperature rose. Additionally, we analyzed the excess energy distribution of the C2H5+ fragment with respect to temperature to investigate the indirect reaction pathway of C2H5+ → H2 + C2H3+. This result suggests that the indirect reaction pathway of C2H5+ → H2 + C2H3+ holds minor significance, although the distribution highly depends on the collisional temperature.
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Affiliation(s)
- Tatsuhiro Murakami
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (S.T.); (Y.K.)
- Department of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Soma Takahashi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (S.T.); (Y.K.)
| | - Yuya Kikuma
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (S.T.); (Y.K.)
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (S.T.); (Y.K.)
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Murakami T, Ibuki S, Hashimoto Y, Kikuma Y, Takayanagi T. Dynamics study of the post-transition-state-bifurcation process of the (HCOOH)H + → CO + H 3O +/HCO + + H 2O dissociation: application of machine-learning techniques. Phys Chem Chem Phys 2023; 25:14016-14027. [PMID: 37161528 DOI: 10.1039/d3cp00252g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The process of protonated formic acid dissociating from the transition state was studied using ring-polymer molecular dynamics (RPMD), classical MD, and quasi-classical trajectory (QCT) simulations. Temperature had a strong influence on the branching fractions for the HCO+ + H2O and CO + H3O+ dissociation channels. The RPMD and classical MD simulations showed similar behavior, but the QCT dynamics were significantly different owing to the excess energies in the quasi-classical trajectories. Machine-learning analysis identified several key features in the phase information of the vibrational motions at the transition state. We found that the initial configuration and momentum of a hydrogen atom connected to a carbon atom and the shrinking coordinate of the CO bond at the transition state play a role in the dynamics of HCO+ + H2O production.
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Affiliation(s)
- Tatsuhiro Murakami
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama, 338-8570, Japan.
- Department of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo, 102-8554, Japan
| | - Shunichi Ibuki
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama, 338-8570, Japan.
| | - Yu Hashimoto
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama, 338-8570, Japan.
| | - Yuya Kikuma
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama, 338-8570, Japan.
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama, 338-8570, Japan.
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Braunstein M, Bonnet L. An efficient algorithm for capturing quantum effects in classical reactive scattering: application to D + H+3 → H 2D + + H. Phys Chem Chem Phys 2023; 25:1602-1605. [PMID: 36541279 DOI: 10.1039/d2cp05108g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Motivated by a recent semiclassical analysis of chemical reaction thresholds [Bonnet et al., J. Chem. Phys., 2022, 157, 094114], we present an efficient algorithm for including zero-point energy (ZPE) effects in classical reactive scattering. The algorithm is an extension of the quasi-classical trajectory (QCT) Gaussian binning method. We apply it to the astrophysically important D + H+3 reaction, where there are significant quantum effects and where application of other methods is problematic [Braunstein et al., Phys. Chem. Chem. Phys., 2022, 24, 5489]. The rate constants computed with the new, general algorithm closely match recent Ring Polymer Molecular Dynamics (RPMD) [Bulut et al., J. Phys. Chem. A, 2019, 123, 8766] and experimentally derived [Bowen et al., J. Chem. Phys., 2021, 154, 084307] ones spanning ∼4 orders of magnitude from 70 to 1500 K.
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Affiliation(s)
- Matthew Braunstein
- Spectral Sciences Incorporated, 4 Fourth Avenue, Burlington, MA 01824, USA.
| | - Laurent Bonnet
- CNRS, Université de Bordeaux, ISM, UMR 5255, F-33400 Talence, France.
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Murakami T, Iida R, Hashimoto Y, Takahashi Y, Takahashi S, Takayanagi T. Ring-Polymer Molecular Dynamics and Kinetics for the H – + C 2H 2 → H 2 + C 2H – Reaction Using the Full-Dimensional Potential Energy Surface. J Phys Chem A 2022; 126:9244-9258. [DOI: 10.1021/acs.jpca.2c05851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Tatsuhiro Murakami
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
- Department of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo102-8554, Japan
| | - Ryusei Iida
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
| | - Yu Hashimoto
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
| | - Yukinobu Takahashi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
| | - Soma Takahashi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City, Saitama338-8570, Japan
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5
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Wu LY, Miossec C, Heazlewood BR. Low-temperature reaction dynamics of paramagnetic species in the gas phase. Chem Commun (Camb) 2022; 58:3240-3254. [PMID: 35188499 PMCID: PMC8902758 DOI: 10.1039/d1cc06394d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/12/2022] [Indexed: 12/12/2022]
Abstract
Radicals are abundant in a range of important gas-phase environments. They are prevalent in the atmosphere, in interstellar space, and in combustion processes. As such, understanding how radicals react is essential for the development of accurate models of the complex chemistry occurring in these gas-phase environments. By controlling the properties of the colliding reactants, we can also gain insights into how radical reactions occur on a fundamental level. Recent years have seen remarkable advances in the breadth of experimental methods successfully applied to the study of reaction dynamics involving paramagnetic species-from improvements to the well-known crossed molecular beams approach to newer techniques involving magnetically guided and decelerated beams. Coupled with ever-improving theoretical methods, quantum features are being observed and interesting insights into reaction dynamics are being uncovered in an increasingly diverse range of systems. In this highlight article, we explore some of the exciting recent developments in the study of chemical dynamics involving paramagnetic species. We focus on low-energy reactive collisions involving neutral radical species, where the reaction parameters are controlled. We conclude by identifying some of the limitations of current methods and exploring possible new directions for the field.
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Affiliation(s)
- Lok Yiu Wu
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Chloé Miossec
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Brianna R Heazlewood
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
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Braunstein M, Bonnet L, Roncero O. Capturing quantum effects with quasi-classical trajectories in the D + H+3 → H 2D + + H reaction. Phys Chem Chem Phys 2022; 24:5489-5505. [PMID: 35171152 DOI: 10.1039/d1cp04244k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present quasi-classical trajectory (QCT) cross sections, rate constants, and product state distributions for the D + H+3 → H2D+ + H reaction. Using the same H+4 potential surface, the rate constants obtained from several QCT-based methods correcting for zero-point effects by Gaussian binning the product H2D+ are compared to ring polymer molecular dynamics (RPMD) rate constants [Bulut et al., J. Phys. Chem. A, 2019, 123, 8766] which include quantum effects and to recent experimentally derived rate constants [Bowen et al., J. Chem. Phys., 2021, 154, 084307]. QCT with standard binning predicts rate constants that increase slowly as the temperature decreases from 1500 to 100 K. In contrast, the RPMD rate constants decrease rapidly with decreasing temperature. By 100 K, the QCT standard binning rate constant is more than 3 orders of magnitude larger than the RPMD rate constant. We show that QCT with Gaussian binning and proper normalization captures the zero-point effects and reproduces the RPMD rate constants over a large temperature range. Furthermore, the simple technique of counting only reactive trajectories with vibrational energy above the product zero-point energy matches the RPMD results well down to ∼300 K. The present Gaussian binned rate constants are in fair agreement with new experimentally derived rate constants from 100 to 1500 K. However, because the Gaussian binned rate constants do not include tunneling, important at lower temperatures, and the RPMD and experimentally derived rate constants have significant differences, the roles of the competing effects of zero-point energy, internal excitation of the H+3, and quantum tunneling are not simple and require further study for a consistent picture of the dynamics. Since rate constants for complex forming reactions, such as the title reaction, are difficult to converge with RPMD, alternative QCT-based methods, which include quantum effects and in addition provide product state distributions as described here, are highly desirable.
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Affiliation(s)
- Matthew Braunstein
- Spectral Sciences Incorporated, 4 Fourth Avenue, Burlington, MA 01824, USA.
| | - Laurent Bonnet
- CNRS, Université de Bordeaux, ISM, UMR 5255, F-33400 Talence, France
| | - Octavio Roncero
- Instituto de Fisica Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, 28006 Madrid, Spain
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7
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Zhu Y, Li R, Song H. Kinetic and dynamic studies of the NH 2+ + H 2 reaction on a high-level ab initio potential energy surface. Phys Chem Chem Phys 2022; 24:25663-25672. [DOI: 10.1039/d2cp03859e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The dynamics and kinetics of the NH2+ + H2 reaction are investigated on a newly developed ab initio potential energy surface using the quasi-classical trajectory method.
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Affiliation(s)
- Yongfa Zhu
- School of Chemistry and Chemical Engineering, Hubei Polytechnic University, Huangshi 435003, China
| | - Rui Li
- School of Chemistry and Chemical Engineering, Hubei Polytechnic University, Huangshi 435003, China
| | - Hongwei Song
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
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8
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Saito K, Hashimoto Y, Takayanagi T. Ring-Polymer Molecular Dynamics Calculations of Thermal Rate Coefficients and Branching Ratios for the Interstellar H 3+ + CO → H 2 + HCO +/HOC + Reaction and Its Deuterated Analogue. J Phys Chem A 2021; 125:10750-10756. [PMID: 34918514 DOI: 10.1021/acs.jpca.1c09160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction between H3+ and CO is important in understanding the H3+ destruction mechanism in the interstellar medium. In this work, thermal rate coefficients for the H3+ + CO and D3+ + CO reactions are calculated using ring-polymer molecular dynamics (RPMD) on a high-level machine-learning potential energy surface. The RPMD results agree well with the classical molecular dynamics results, where nuclear quantum effects are completely ignored, whereas the agreement between the RPMD results and the previous quasi-classical trajectory is good only at low temperatures. The calculated [HCO+]/[HOC+] product branching ratios decrease as the temperature increases, and the product branching is exclusively determined by the initial collisional orientation, which governs the formation of an ion-dipole complex, H3+···CO or H3+···OC, that dissociates into H2 + HCO+ or H2 + HOC+, respectively, via a direct mechanism. However, the contribution of the indirect mechanism via the rearrangement between H3+···CO and H3+···OC increases as the temperature increases, although its absolute fraction is small.
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Affiliation(s)
- Kohei Saito
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama 338-8570, Japan
| | - Yu Hashimoto
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama 338-8570, Japan
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama 338-8570, Japan
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9
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Pan M, Xiang H, Li Y, Song H. Study on the kinetics and dynamics of the H 2 + NH 2- reaction on a high-level ab initio potential energy surface. Phys Chem Chem Phys 2021; 23:17848-17855. [PMID: 34612274 DOI: 10.1039/d1cp02423j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase ion-molecule reactions play major roles in many fields of chemistry and physics. The reaction of an amino radical anion with a hydrogen molecule is one of the simplest proton transfer reactions involving anions. A globally accurate full-dimensional potential energy surface (PES) for the NH2- + H2 reaction is developed by the fundamental invariant-neural network method, resulting in a root mean square error of 0.116 kcal mol-1. Quasi-classical trajectory calculations are then carried out on the newly developed PES to give integral cross sections, differential cross sections and thermal rate coefficients. This reaction has two reaction channels, proton transfer and hydrogen exchange. The reactivity of the proton transfer channel is about one or two orders of magnitude stronger than that of the hydrogen exchange channel in the energy range studied. Vibrational excitation of H2 promotes the proton transfer reaction, while fundamental excitation of each vibrational mode of NH2- has a negligible effect. In addition, the theoretical rate coefficients of the proton transfer reaction on the PES show inverse temperature dependence from 150 to 750 K, in accordance with the available experimental results.
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Affiliation(s)
- Mengyi Pan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
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10
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Zhao B. The symmetric C-D stretching spectator mode in the H + CHD 3 → H 2 + CD 3 reaction and its effect on dynamical modeling. Phys Chem Chem Phys 2021; 23:12105-12114. [PMID: 34027536 DOI: 10.1039/d1cp01614h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The symmetric C-D stretching mode is a spectator mode in the H + CHD3 → H2 + CD3 reaction. Effects of multiple vibrational excitations of the CHD3 reactant are studied with the quantum transition-state (QTS) framework and an eight-dimensional (8D) model Hamiltonian developed by Palma and Clary. By including many thermal flux eigenstates, results have been obtained up to high energies, allowing the study of the symmetric C-D stretching spectator mode. A new concept of a state-specific thermal flux operator is proposed to analyze the C-D stretching spectator mode in detail, providing a new and insightful venue for studying transition-state control of chemical reactions. Furthermore, as a spectator mode, whether the C-D stretching motion can be excluded in a seven-dimensional (7D) model has not been fully interrogated, although the 7D model is a reasonable approximation and has provided accurate theoretical predictions. By comparing with available results of full-dimensional calculations, both the 7D and 8D models predict reasonably accurate results. However, the 7D model underestimates the mixing of two vibrational states that are in Fermi resonance. Despite its spectator nature, the C-D stretch is important in the dynamical modeling of chemical reaction systems affected by state mixing.
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Affiliation(s)
- Bin Zhao
- Theoretische Chemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
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Gao LG, Fleming DG, Truhlar DG, Xu X. Large Anharmonic Effects on Tunneling and Kinetics: Reaction of Propane with Muonium. J Phys Chem Lett 2021; 12:4154-4159. [PMID: 33890795 DOI: 10.1021/acs.jpclett.1c01229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Calculations of kinetic isotope effects (KIEs) provide challenging tests of quantal mass effects on reaction rates, and muonium KIEs are the most challenging. Here, we show that it can be very important to include reaction-coordinate-dependent vibrational anharmonicity along the whole reaction path to calculate tunneling probabilities and KIEs. For the reaction of propane with Mu, this decreases both the height and width of the vibrationally adiabatic potential barrier, with both effects increasing the rate constants. Our results agree well with the experimental observations.
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Affiliation(s)
- Lu Gem Gao
- Center for Combustion Energy, Department of Energy and Power Engineering, and Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China
| | - Donald G Fleming
- TRIUMF and Department of Chemistry, University of British Columbia, 4004 Wesbrook Mall, Vancouver, BC V6T 1Z4, Canada
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Xuefei Xu
- Center for Combustion Energy, Department of Energy and Power Engineering, and Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084, China
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12
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Mazo-Sevillano PD, Aguado A, Roncero O. Neural network potential energy surface for the low temperature ring polymer molecular dynamics of the H 2CO + OH reaction. J Chem Phys 2021; 154:094305. [PMID: 33685156 DOI: 10.1063/5.0044009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A new potential energy surface (PES) and dynamical study of the reactive process of H2CO + OH toward the formation of HCO + H2O and HCOOH + H are presented. In this work, a source of spurious long range interactions in symmetry adapted neural network (NN) schemes is identified, which prevents their direct application for low temperature dynamical studies. For this reason, a partition of the PES into a diabatic matrix plus a NN many-body term has been used, fitted with a novel artificial neural network scheme that prevents spurious asymptotic interactions. Quasi-classical trajectory (QCT) and ring polymer molecular dynamics (RPMD) studies have been carried on this PES to evaluate the rate constant temperature dependence for the different reactive processes, showing good agreement with the available experimental data. Of special interest is the analysis of the previously identified trapping mechanism in the RPMD study, which can be attributed to spurious resonances associated with excitations of the normal modes of the ring polymer.
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Affiliation(s)
- Pablo Del Mazo-Sevillano
- Unidad Asociada UAM-CSIC, Departamento de Química Física Aplicada, Facultad de Ciencias M-14, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Alfredo Aguado
- Unidad Asociada UAM-CSIC, Departamento de Química Física Aplicada, Facultad de Ciencias M-14, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Octavio Roncero
- Instituto de Física Fundamental (IFF-CSIC), CSIC, Serrano 123, 28006 Madrid, Spain
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Bowen KP, Hillenbrand PM, Liévin J, Savin DW, Urbain X. Dynamics of the isotope exchange reaction of D with H 3 +, H 2D +, and D 2H . J Chem Phys 2021; 154:084307. [PMID: 33639774 DOI: 10.1063/5.0038434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have measured the merged-beams rate coefficient for the titular isotope exchange reactions as a function of the relative collision energy in the range of ∼3 meV-10 eV. The results appear to scale with the number of available sites for deuteration. We have performed extensive theoretical calculations to characterize the zero-point energy corrected reaction path. Vibrationally adiabatic minimum energy paths were obtained using a combination of unrestricted quadratic configuration interaction of single and double excitations and internally contracted multireference configuration interaction calculations. The resulting barrier height, ranging from 68 meV to 89 meV, together with the various asymptotes that may be reached in the collision, was used in a classical over-the-barrier model. All competing endoergic reaction channels were taken into account using a flux reduction factor. This model reproduces all three experimental sets quite satisfactorily. In order to generate thermal rate coefficients down to 10 K, the internal excitation energy distribution of each H3 + isotopologue is evaluated level by level using available line lists and accurate spectroscopic parameters. Tunneling is accounted for by a direct inclusion of the exact quantum tunneling probability in the evaluation of the cross section. We derive a thermal rate coefficient of <1×10-12 cm3 s-1 for temperatures below 44 K, 86 K, and 139 K for the reaction of D with H3 +, H2D+, and D2H+, respectively, with tunneling effects included. The derived thermal rate coefficients exceed the ring polymer molecular dynamics prediction of Bulut et al. [J. Phys. Chem. A 123, 8766 (2019)] at all temperatures.
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Affiliation(s)
- K P Bowen
- Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA
| | - P-M Hillenbrand
- Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA
| | - J Liévin
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Université Libre de Bruxelles, B-1050 Brussels, Belgium
| | - D W Savin
- Columbia Astrophysics Laboratory, Columbia University, New York, New York 10027, USA
| | - X Urbain
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
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