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Shan X, Burd TAH, Clary DC. New Developments in Semiclassical Transition-State Theory. J Phys Chem A 2019; 123:4639-4657. [DOI: 10.1021/acs.jpca.9b01987] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Timothy A. H. Burd
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - David C. Clary
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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2
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Clary DC. Spiers Memorial Lecture : Introductory lecture: quantum dynamics of chemical reactions. Faraday Discuss 2018; 212:9-32. [DOI: 10.1039/c8fd00131f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This Spiers Memorial Lecture discusses quantum effects that can be calculated and observed in the chemical reactions of small molecules.
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Affiliation(s)
- David C. Clary
- Physical and Theoretical Chemistry Laboratory
- Department of Chemistry
- University of Oxford
- Oxford
- UK
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3
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4
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Vikár A, Nagy T, Lendvay G. Testing the Palma-Clary Reduced Dimensionality Model Using Classical Mechanics on the CH4 + H → CH3 + H2 Reaction. J Phys Chem A 2016; 120:5083-93. [PMID: 26918703 DOI: 10.1021/acs.jpca.6b00346] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Application of exact quantum scattering methods in theoretical reaction dynamics of bimolecular reactions is limited by the complexity of the equations of nuclear motion to be solved. Simplification is often achieved by reducing the number of degrees of freedom to be explicitly handled by freezing the less important spectator modes. The reaction cross sections obtained in reduced-dimensionality (RD) quantum scattering methods can be used in the calculation of rate coefficients, but their physical meaning is limited. The accurate test of the performance of a reduced-dimensionality method would be a comparison of the RD cross sections with those obtained in accurate full-dimensional (FD) calculations, which is not feasible because of the lack of complete full-dimensional results. However, classical mechanics allows one to perform reaction dynamics calculations using both the RD and the FD model. In this paper, an RD versus FD comparison is made for the 8-dimensional Palma-Clary model on the example of four isotopologs of the CH4 + H → CH3 + H2 reaction, which has 12 internal dimensions. In the Palma-Clary model, the only restriction is that the methyl group is confined to maintain C3v symmetry. Both RD and FD opacity and excitation functions as well as differential cross sections were calculated using the quasiclassical trajectory method. The initial reactant separation has been handled according to our one-period averaging method [ Nagy et al. J. Chem. Phys. 2016, 144, 014104 ]. The RD and FD excitation functions were found to be close to each other for some isotopologs, but in general, the RD reactivity parameters are lower than the FD reactivity parameters beyond statistical error, and for one of the isotopologs, the deviation is significant. This indicates that the goodness of RD cross sections cannot be taken for granted.
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Affiliation(s)
- Anna Vikár
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar tudósok körútja 2, H-1117 Budapest, Hungary
| | - Tibor Nagy
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar tudósok körútja 2, H-1117 Budapest, Hungary
| | - György Lendvay
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar tudósok körútja 2, H-1117 Budapest, Hungary
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5
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Greene SM, Shan X, Clary DC. Rate constants of chemical reactions from semiclassical transition state theory in full and one dimension. J Chem Phys 2016; 144:244116. [DOI: 10.1063/1.4954840] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Samuel M. Greene
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - David C. Clary
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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6
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Greene SM, Shan X, Clary DC. An investigation of one- versus two-dimensional semiclassical transition state theory for H atom abstraction and exchange reactions. J Chem Phys 2016; 144:084113. [DOI: 10.1063/1.4942161] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Samuel M. Greene
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - David C. Clary
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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7
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Wang Y, Li J, Chen L, Lu Y, Yang M, Guo H. Mode specific dynamics of the H2 + CH3 → H + CH4 reaction studied using quasi-classical trajectory and eight-dimensional quantum dynamics methods. J Chem Phys 2015; 143:154307. [DOI: 10.1063/1.4933240] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yan Wang
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
- School of Chemical and Environmental Engineering, Hubei University for Nationalities, Enshi 445000, China
| | - Jun Li
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Liuyang Chen
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Minghui Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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8
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Greene SM, Shan X, Clary DC. Reduced-Dimensionality Semiclassical Transition State Theory: Application to Hydrogen Atom Abstraction and Exchange Reactions of Hydrocarbons. J Phys Chem A 2015; 119:12015-27. [DOI: 10.1021/acs.jpca.5b04379] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Samuel M. Greene
- Physical and Theoretical Chemistry
Laboratory, Department of Chemistry, University of Oxford, South Parks
Road, Oxford, OX1 3QZ, United Kingdom
| | - Xiao Shan
- Physical and Theoretical Chemistry
Laboratory, Department of Chemistry, University of Oxford, South Parks
Road, Oxford, OX1 3QZ, United Kingdom
| | - David C. Clary
- Physical and Theoretical Chemistry
Laboratory, Department of Chemistry, University of Oxford, South Parks
Road, Oxford, OX1 3QZ, United Kingdom
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9
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Li J, Chen J, Zhao Z, Xie D, Zhang DH, Guo H. A permutationally invariant full-dimensional ab initio potential energy surface for the abstraction and exchange channels of the H + CH4 system. J Chem Phys 2015; 142:204302. [DOI: 10.1063/1.4921412] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jun Li
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Jun Chen
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhiqiang Zhao
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Dong H. Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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10
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Oueslati I, Kerkeni B, Tchang-Brillet WÜL, Feautrier N. Quantum scattering study of the abstraction reaction of H atoms from tetramethylsilane. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Shan X, Clary DC. Quantum Dynamics of the Abstraction Reaction of H with Cyclopropane. J Phys Chem A 2014; 118:10134-43. [DOI: 10.1021/jp5087174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiao Shan
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, U.K
| | - David C. Clary
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, U.K
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12
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Zhang Z, Zhang DH. Effects of reagent rotational excitation on the H + CHD3 → H2 + CD3 reaction: A seven dimensional time-dependent wave packet study. J Chem Phys 2014; 141:144309. [DOI: 10.1063/1.4897308] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zhaojun Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Dong H. Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
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13
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Wang Y, Li J, Guo H, Yang M. A comparison study of the H + CH4 and H + SiH4 reactions with eight-dimensional quantum dynamics: normal mode versus local mode in the reactant molecule vibration. Theor Chem Acc 2014. [DOI: 10.1007/s00214-014-1555-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Zhang Z, Chen J, Liu S, Zhang DH. Accuracy of the centrifugal sudden approximation in the H + CHD3 → H2 + CD3 reaction. J Chem Phys 2014; 140:224304. [DOI: 10.1063/1.4881517] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Zhaojun Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Jun Chen
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Shu Liu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Dong H. Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
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15
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Pan H, Yang J, Zhang D, Shuai Q, Dai D, Wu G, Jiang B, Yang X. Effect of antisymmetric C–H stretching excitation on the dynamics of O(1D) + CH4 → OH + CH3. J Chem Phys 2014. [DOI: 10.1063/1.4871135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Oueslati I, Kerkeni B, Spielfiedel A, Tchang-Brillet WÜL, Feautrier N. Ab Initio Investigation of the Abstraction Reactions by H and D from Tetramethylsilane and Its Deuterated Substitutions. J Phys Chem A 2014; 118:791-802. [DOI: 10.1021/jp407310c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I. Oueslati
- Faculté
des Sciences de Tunis, Département de Physique,
(LPMC), Université de Tunis El Manar, 2092 Tunis, Tunisia
- LERMA,
UMR8112-CNRS, Observatoire de Paris, Université Pierre et Marie Curie, 5 place Jules Janssen, 92195 Meudon Cedex, France
| | - B. Kerkeni
- Faculté
des Sciences de Tunis, Département de Physique,
(LPMC), Université de Tunis El Manar, 2092 Tunis, Tunisia
- Institut Supérieur
des Arts Multimédia de la Manouba, Université de la Manouba, 2010 la Manouba, Tunisia
| | - A. Spielfiedel
- LERMA,
UMR8112-CNRS, Observatoire de Paris, Université Pierre et Marie Curie, 5 place Jules Janssen, 92195 Meudon Cedex, France
| | - W.-Ü L. Tchang-Brillet
- LERMA,
UMR8112-CNRS, Observatoire de Paris, Université Pierre et Marie Curie, 5 place Jules Janssen, 92195 Meudon Cedex, France
| | - N. Feautrier
- LERMA,
UMR8112-CNRS, Observatoire de Paris, Université Pierre et Marie Curie, 5 place Jules Janssen, 92195 Meudon Cedex, France
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17
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Welsch R, Manthe U. Fast Shepard interpolation on graphics processing units: Potential energy surfaces and dynamics for H + CH4 → H2 + CH3. J Chem Phys 2013; 138:164118. [DOI: 10.1063/1.4802059] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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18
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Liu S, Chen J, Zhang Z, Zhang DH. Communication: A six-dimensional state-to-state quantum dynamics study of the H + CH4 → H2 + CH3 reaction (J = 0). J Chem Phys 2013; 138:011101. [DOI: 10.1063/1.4774116] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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19
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Welsch R, Manthe U. Reaction dynamics with the multi-layer multi-configurational time-dependent Hartree approach: H + CH4 → H2 + CH3 rate constants for different potentials. J Chem Phys 2012; 137:244106. [DOI: 10.1063/1.4772585] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Fleming DG, Arseneau DJ, Sukhorukov O, Brewer JH, Mielke SL, Truhlar DG, Schatz GC, Garrett BC, Peterson KA. Kinetics of the reaction of the heaviest hydrogen atom with H2, the4Heμ + H2→4HeμH + H reaction: Experiments, accurate quantal calculations, and variational transition state theory, including kinetic isotope effects for a factor of 36.1 in isotopic mass. J Chem Phys 2011; 135:184310. [DOI: 10.1063/1.3657440] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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von Horsten HF, Banks ST, Clary DC. An efficient route to thermal rate constants in reduced dimensional quantum scattering simulations: Applications to the abstraction of hydrogen from alkanes. J Chem Phys 2011; 135:094311. [DOI: 10.1063/1.3625960] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Zhou Y, Wang C, Zhang DH. Effects of reagent vibrational excitation on the dynamics of the H + CHD3 → H2 + CD3 reaction: A seven-dimensional time-dependent wave packet study. J Chem Phys 2011; 135:024313. [DOI: 10.1063/1.3609923] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Remmert SM, Banks ST, Harvey JN, Orr-Ewing AJ, Clary DC. Reduced dimensionality spin-orbit dynamics of CH3 + HCl ⇌ CH4 + Cl on ab initio surfaces. J Chem Phys 2011; 134:204311. [DOI: 10.1063/1.3592732] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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24
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Suleimanov YV, Collepardo-Guevara R, Manolopoulos DE. Bimolecular reaction rates from ring polymer molecular dynamics: application to H + CH4 → H2 + CH3. J Chem Phys 2011; 134:044131. [PMID: 21280711 DOI: 10.1063/1.3533275] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In a recent paper, we have developed an efficient implementation of the ring polymer molecular dynamics (RPMD) method for calculating bimolecular chemical reaction rates in the gas phase, and illustrated it with applications to some benchmark atom-diatom reactions. In this paper, we show that the same methodology can readily be used to treat more complex polyatomic reactions in their full dimensionality, such as the hydrogen abstraction reaction from methane, H + CH(4) → H(2) + CH(3). The present calculations were carried out using a modified and recalibrated version of the Jordan-Gilbert potential energy surface. The thermal rate coefficients obtained between 200 and 2000 K are presented and compared with previous results for the same potential energy surface. Throughout the temperature range that is available for comparison, the RPMD approximation gives better agreement with accurate quantum mechanical (multiconfigurational time-dependent Hartree) calculations than do either the centroid density version of quantum transition state theory (QTST) or the quantum instanton (QI) model. The RPMD rate coefficients are within a factor of 2 of the exact quantum mechanical rate coefficients at temperatures in the deep tunneling regime. These results indicate that our previous assessment of the accuracy of the RPMD approximation for atom-diatom reactions remains valid for more complex polyatomic reactions. They also suggest that the sensitivity of the QTST and QI rate coefficients to the choice of the transition state dividing surface becomes more of an issue as the dimensionality of the reaction increases.
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Affiliation(s)
- Yury V Suleimanov
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
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25
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Kerkeni B, Clary DC. Quantum dynamics and kinetics of the abstraction reactions by H atoms of primary and secondary hydrogens in C3H8. Mol Phys 2011. [DOI: 10.1080/00268970500044764] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Boutheina Kerkeni
- a Physical and Theoretical Chemistry Laboratory , University of Oxford , Oxford , OX1 3QZ , UK
| | - David C. Clary
- a Physical and Theoretical Chemistry Laboratory , University of Oxford , Oxford , OX1 3QZ , UK
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26
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Zhou Y, Fu B, Wang C, Collins MA, Zhang DH. Ab initio potential energy surface and quantum dynamics for the H + CH4 → H2 + CH3 reaction. J Chem Phys 2011; 134:064323. [DOI: 10.1063/1.3552088] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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von Horsten HF, Clary DC. Reactive resonances in the F + CHD3 reaction—a quantum dynamics study. Phys Chem Chem Phys 2011; 13:4340-56. [DOI: 10.1039/c0cp02661a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Schiffel G, Manthe U. A transition state view on reactive scattering: Initial state-selected reaction probabilities for the H+CH4→H2+CH3 reaction studied in full dimensionality. J Chem Phys 2010; 133:174124. [DOI: 10.1063/1.3489409] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Hennig C, Schmatz S. Rotational effects in complex-forming bimolecular substitution reactions: A quantum-mechanical approach. J Chem Phys 2010; 131:224303. [PMID: 20001032 DOI: 10.1063/1.3264684] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The quantum dynamics of the complex-forming S(N)2 reaction Cl(-)+CH(3)Br-->ClCH(3)+Br(-) is studied with emphasis on rotational effects. The pseudotriatomic system Cl-Me-Br is treated with a corresponding three-dimensional (3D) potential energy surface as a function of the two scattering coordinates and the enclosed angle where the geometry of the methyl group Me is optimized at each point. The 3D space is divided into three different parts, the interaction region, an intermediate region, and the asymptotic region. In line with simple classical-mechanical arguments and previous classical trajectory calculations, initial rotational motion of CH(3)Br seemingly decreases the reaction probability. However, the dynamical inclusion of the rotational degree of freedom and the presence of the many rovibrational product states overall lead to a large increase in reactivity compared to our previous collinear study on this reaction. If the reactant is rotationally excited, the higher vibrational product states are depleted in favor of lower-lying levels. Starting the reaction with rotationless reactants may end up in significant rotational excitation in the product molecules (translation-to-rotation energy transfer). On the other hand, initial rotational energy in rotationally highly excited reactants is to a large amount converted into translational and vibrational energy. The average amount of rotational energy in the products shows a twofold vibrational excitation-independent saturation (i.e., memorylessness), with respect to both initial rotational excitation and translational energy. Since only about one-half of all reactant states end in rotationless products, the reaction probability should be increased by a factor of 2; the actually larger reactivity points to other dynamical effects that play an important role in the reaction.
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Affiliation(s)
- Carsten Hennig
- Institut für Physikalische Chemie, Universität Göttingen, Germany
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30
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Banks ST, Tautermann CS, Remmert SM, Clary DC. An improved treatment of spectator mode vibrations in reduced dimensional quantum dynamics: Application to the hydrogen abstraction reactions μ+CH4, H+CH4, D+CH4, and CH3+CH4. J Chem Phys 2009; 131:044111. [DOI: 10.1063/1.3177380] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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31
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Andersson S, Nyman G, Arnaldsson A, Manthe U, Jónsson H. Comparison of Quantum Dynamics and Quantum Transition State Theory Estimates of the H + CH4 Reaction Rate. J Phys Chem A 2009; 113:4468-78. [DOI: 10.1021/jp811070w] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stefan Andersson
- Department of Chemistry, Physical Chemistry, University of Gothenburg, SE-41296 Gothenburg, Sweden, Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland, and Theoretische Chemie, Universität Bielefeld, Universitätstrasse 25, D-33615 Bielefeld, Germany
| | - Gunnar Nyman
- Department of Chemistry, Physical Chemistry, University of Gothenburg, SE-41296 Gothenburg, Sweden, Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland, and Theoretische Chemie, Universität Bielefeld, Universitätstrasse 25, D-33615 Bielefeld, Germany
| | - Andri Arnaldsson
- Department of Chemistry, Physical Chemistry, University of Gothenburg, SE-41296 Gothenburg, Sweden, Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland, and Theoretische Chemie, Universität Bielefeld, Universitätstrasse 25, D-33615 Bielefeld, Germany
| | - Uwe Manthe
- Department of Chemistry, Physical Chemistry, University of Gothenburg, SE-41296 Gothenburg, Sweden, Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland, and Theoretische Chemie, Universität Bielefeld, Universitätstrasse 25, D-33615 Bielefeld, Germany
| | - Hannes Jónsson
- Department of Chemistry, Physical Chemistry, University of Gothenburg, SE-41296 Gothenburg, Sweden, Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland, and Theoretische Chemie, Universität Bielefeld, Universitätstrasse 25, D-33615 Bielefeld, Germany
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32
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Remmert SM, Banks ST, Clary DC. Reduced Dimensionality Quantum Dynamics of CH3 + CH4 → CH4 + CH3: Symmetric Hydrogen Exchange on an Ab Initio Potential. J Phys Chem A 2009; 113:4255-64. [DOI: 10.1021/jp810803k] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sarah M. Remmert
- Department of Chemistry, University of Oxford, PTCL, South Parks Road, Oxford, OX13QZ, United Kingdom
| | - Simon T. Banks
- Department of Chemistry, University of Oxford, PTCL, South Parks Road, Oxford, OX13QZ, United Kingdom
| | - David C. Clary
- Department of Chemistry, University of Oxford, PTCL, South Parks Road, Oxford, OX13QZ, United Kingdom
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33
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Banks ST, Clary DC. Chemical reaction surface vibrational frequencies evaluated in curvilinear internal coordinates: Application to H+CH4⇌H2+CH3. J Chem Phys 2009; 130:024106. [DOI: 10.1063/1.3052076] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Aryanpour M, Dhanda A, Pitsch H. An algorithm for mass matrix calculation of internally constrained molecular geometries. J Chem Phys 2008; 128:044113. [DOI: 10.1063/1.2827489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Zhang L, Lu Y, Lee SY, Zhang DH. A transition state wave packet study of the H+CH4 reaction. J Chem Phys 2007; 127:234313. [DOI: 10.1063/1.2812553] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Albu TV, Espinosa-García J, Truhlar DG. Computational Chemistry of Polyatomic Reaction Kinetics and Dynamics: The Quest for an Accurate CH5 Potential Energy Surface. Chem Rev 2007; 107:5101-32. [DOI: 10.1021/cr078026x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Titus V. Albu
- Department of Chemistry, Box 5055, Tennessee Technological University, Cookeville, Tennessee 38505
| | | | - Donald G. Truhlar
- Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
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37
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Quantum dynamics study of the Langmuir–Hinshelwood H+H recombination mechanism and H2 formation on a graphene model surface. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.06.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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38
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Zhang XQ, Cui Q, Zhang JZH, Han KL. Quantum dynamics study of H+NH3→H2+NH2 reaction. J Chem Phys 2007; 126:234304. [PMID: 17600417 DOI: 10.1063/1.2745796] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report in this paper a quantum dynamics study for the reaction H+NH3-->NH2+H2 on the potential energy surface of Corchado and Espinosa-Garcia [J. Chem. Phys. 106, 4013 (1997)]. The quantum dynamics calculation employs the semirigid vibrating rotor target model [J. Z. H. Zhang, J. Chem. Phys. 111, 3929 (1999)] and time-dependent wave packet method to propagate the wave function. Initial state-specific reaction probabilities are obtained, and an energy correction scheme is employed to account for zero point energy changes for the neglected degrees of freedom in the dynamics treatment. Tunneling effect is observed in the energy dependency of reaction probability, similar to those found in H+CH4 reaction. The influence of rovibrational excitation on reaction probability and stereodynamical effect are investigated. Reaction rate constants from the initial ground state are calculated and are compared to those from the transition state theory and experimental measurement.
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Affiliation(s)
- Xu Qiang Zhang
- Department of Chemistry, New York University, New York, New York 10003, USA
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39
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Kerkeni B, Clary DC. Quantum scattering study of the abstraction reactions of H atoms from CH3NH2. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.02.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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40
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van Harrevelt R, Nyman G, Manthe U. Accurate quantum calculations of the reaction rates for H∕D+CH4. J Chem Phys 2007; 126:084303. [PMID: 17343444 DOI: 10.1063/1.2464102] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In previous work [T. Wu, H. J. Werner, and U. Manthe, Science 306, 2227 (2004)], accurate quantum reaction rate calculations of the rate constant for the H+CH4-->CH3+H2 reaction have been presented. Both the electronic structure calculations and the nuclear dynamics calculations are converged with respect to the basis sets employed. In this paper, the authors apply the same methodology to an isotopic variant of this reaction: D+CH4-->CH3+HD. Accurate rate constants are presented for temperatures between 250 and 400 K. For temperatures between 400 and 800 K, they use a harmonic extrapolation to obtain approximate rate constants for H/D+CH4. The calculations suggest that the experimentally reported rate constants for D+CH4 are about a factor of 10-20 too high. For H+CH4, more accurate experiments are available and agreement is much better: the difference is less than a factor of 2.6. The kinetic isotope effect for the H/D+CH4 reactions is studied and compared with experiment and transition state theory (TST) calculations. Harmonic TST was found to provide a good description of the kinetic isotope effect.
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Affiliation(s)
- Rob van Harrevelt
- Theoretische Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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41
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Fernandez-Ramos A, Miller JA, Klippenstein SJ, Truhlar DG. Modeling the kinetics of bimolecular reactions. Chem Rev 2007; 106:4518-84. [PMID: 17091928 DOI: 10.1021/cr050205w] [Citation(s) in RCA: 393] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Antonio Fernandez-Ramos
- Departamento de Quimica Fisica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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42
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Banks ST, Clary DC. Reduced dimensionality quantum dynamics of Cl + CH4? HCl + CH3 on an ab initio potential. Phys Chem Chem Phys 2007; 9:933-43. [PMID: 17301883 DOI: 10.1039/b615460c] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the reaction Cl + CH(4)--> HCl + CH(3) using a 2-D potential energy surface obtained by fitting a double Morse analytical function to high level (CCSD(T)/cc-pVTZ//MP2/cc-pVTZ)ab initio data. Dynamics simulations are performed in hyperspherical coordinates with the close-coupled equations being solved using R-matrix propagation. Quantum contributions from spectator modes are included via a harmonic zero-point correction to the ab initio data prior to fitting the potential. This is the first time this method has been applied to a heavy-light-heavy reaction and the first time it has been used to study differential cross sections. We find thermal rate constants and state-to-state differential cross sections which are in good agreement with experimental data. We discuss the applicability of our method to the study of kinetic isotope effects (KIEs), which we derive for the CH(4)/CD(4) substitution. The calculated KIE compares favourably with experiment. Finally, we discuss the sensitivity of the results of dynamics simulations on the accuracy of the fitted potential.
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Affiliation(s)
- Simon T Banks
- Physical and Theoretical Chemistry Department, University of Oxford, South Parks Road, Oxford, UK.
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43
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Abstract
This paper is an overview of the theory of reactive scattering, with emphasis on fully quantum mechanical theories that have been developed to describe simple chemical reactions, especially atom-diatom reactions. We also describe related quasiclassical trajectory applications, and in all of this review the emphasis is on methods and applications concerned with state-resolved reaction dynamics. The review first provides an overview of the development of the theory, including a discussion of computational methods based on coupled channel calculations, variational methods, and wave packet methods. Choices of coordinates, including the use of hyperspherical coordinates are discussed, as are basis set and discrete variational representations. The review also summarizes a number of applications that have been performed, especially the two most comprehensively studied systems, H+H2 and F+H2, along with brief discussions of a large number of other systems, including other hydrogen atom transfer reactions, insertion reactions, electronically nonadiabatic reactions, and reactions involving four or more atoms. For each reaction we describe the method used and important new physical insight extracted from the results.
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Affiliation(s)
- Wenfang Hu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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44
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Rangel C, Corchado JC, Espinosa-García J. Quasi-Classical Trajectory Calculations Analyzing the Reactivity and Dynamics of Asymmetric Stretch Mode Excitations of Methane in the H + CH4 Reaction. J Phys Chem A 2006; 110:10375-83. [PMID: 16942042 DOI: 10.1021/jp063118w] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An exhaustive dynamics study was performed at two collision energies, 1.52 and 2.20 eV, analyzing the effects of the asymmetric (nu3) stretch mode excitation in the reactivity and dynamics of the gas-phase H + CH4 reaction. Quasi-classical trajectory (QCT) calculations, including corrections to avoid zero-point energy leakage along the trajectories, were performed on an analytical potential energy surface previously developed by our group. First, strong coupling between different vibrational modes in the entry channel was observed, indicating that energy can flow between these modes, and therefore that they do not preserve their adiabatic character along the reaction path; i.e., the reaction is nonadiabatic. Second, we found that the reactant vibrational excitation has a significant influence on the vibrational and rotational product distributions. With respect to the vibrational distribution, our results confirm the purely qualitative experimental evidence, although the theoretical results presented here are also quantitative. The rotational distributions are predictive, because no experimental data have been reported. Third, with respect to the reactivity, we found that the nu3 mode excitation by one quantum is more reactive than the ground state by a factor of about 2, independently of the collision energy, and in agreement with the experimental measurement of 3.0 +/- 1.5. Fourth, the state-to-state angular distributions of the products reproduce the experimental behavior at 1.52 eV, where the CH3 products scatter sideways and backward. At 2.20 eV this experimental information is not available, and therefore the results reported here are again predictive. The satisfactory reproduction of a great variety of experimental data by the present QCT study lends confidence to the potential energy surface constructed by our group and to those results whose accuracy cannot be checked by comparison with experiment.
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Affiliation(s)
- Cipriano Rangel
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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45
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Wu T, Werner HJ, Manthe U. Accurate potential energy surface and quantum reaction rate calculations for the H+CH4→H2+CH3 reaction. J Chem Phys 2006; 124:164307. [PMID: 16674135 DOI: 10.1063/1.2189223] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Calculations for the cumulative reaction probability N(E) (for J=0) and the thermal rate constant k(T) of the H+CH(4)-->H(2)+CH(3) reaction are presented. Accurate electronic structure calculations and a converged Shepard-interpolation approach are used to construct a potential energy surface which is specifically designed to allow the precise calculation of k(T) and N(E). Accurate quantum dynamics calculations employing flux correlation functions and multiconfigurational time-dependent Hartree wave packet propagation compute N(E) and k(T) based on this potential energy surface. The present work describes in detail the various convergence test performed to investigate the accuracy of the calculations at each step. These tests demonstrate the predictive power of the present calculations. In addition, approximate approaches for reaction rate calculations are discussed. A quite accurate approximation can be obtained from a potential energy surface which includes only interpolation points on the minimum energy path.
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Affiliation(s)
- Tao Wu
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, People's Republic of China
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46
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Kerkeni B, Clary DC. Quantum dynamics calculations of the Mu+CH4→MuH+CH3 reaction rate constants. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.12.107] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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47
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Chakraborty A, Zhao Y, Lin H, Truhlar DG. Combined valence bond-molecular mechanics potential-energy surface and direct dynamics study of rate constants and kinetic isotope effects for the H+C2H6 reaction. J Chem Phys 2006; 124:044315. [PMID: 16460170 DOI: 10.1063/1.2132276] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This article presents a multifaceted study of the reaction H+C(2)H(6)-->H(2)+C(2)H(5) and three of its deuterium-substituted isotopologs. First we present high-level electronic structure calculations by the W1, G3SX, MCG3-MPWB, CBS-APNO, and MC-QCISD/3 methods that lead to a best estimate of the barrier height of 11.8+/-0.5 kcal/mol. Then we obtain a specific reaction parameter for the MPW density functional in order that it reproduces the best estimate of the barrier height; this yields the MPW54 functional. The MPW54 functional, as well as the MPW60 functional that was previously parametrized for the H+CH(4) reaction, is used with canonical variational theory with small-curvature tunneling to calculate the rate constants for all four ethane reactions from 200 to 2000 K. The final MPW54 calculations are based on curvilinear-coordinate generalized-normal-mode analysis along the reaction path, and they include scaled frequencies and an anharmonic C-C bond torsion. They agree with experiment within 31% for 467-826 K except for a 38% deviation at 748 K; the results for the isotopologs are predictions since these rate constants have never been measured. The kinetic isotope effects (KIEs) are analyzed to reveal the contributions from subsets of vibrational partition functions and from tunneling, which conspire to yield a nonmonotonic temperature dependence for one of the KIEs. The stationary points and reaction-path potential of the MPW54 potential-energy surface are then used to parametrize a new kind of analytical potential-energy surface that combines a semiempirical valence bond formalism for the reactive part of the molecule with a standard molecular mechanics force field for the rest; this may be considered to be either an extension of molecular mechanics to treat a reactive potential-energy surface or a new kind of combined quantum-mechanical/molecular mechanical (QM/MM) method in which the QM part is semiempirical valence bond theory; that is, the new potential-energy surface is a combined valence bond molecular mechanics (CVBMM) surface. Rate constants calculated with the CVBMM surface agree with the MPW54 rate constants within 12% for 534-2000 K and within 23% for 200-491 K. The full CVBMM potential-energy surface is now available for use in variety of dynamics calculations, and it provides a prototype for developing CVBMM potential-energy surfaces for other reactions.
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Affiliation(s)
- Arindam Chakraborty
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
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48
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Abstract
A practical quantum-dynamical method is described for predicting accurate rate constants for general chemical reactions. The ab initio potential energy surfaces for these reactions can be built from a minimal number of grid points (average of 50 points) and expressed in terms of analytical functionals. All the degrees of freedom except the breaking and forming bonds are optimised using the MP2 method with a cc-pVTZ basis set. Single point energies are calculated on the optimised geometries at the CCSD(T) level of theory with the same basis set. The dynamics of these reactions occur on effective reduced dimensionality hyper-surfaces accounting for the zero-point energy of the optimised degrees of freedom. Bonds being broken and formed are treated with explicit hyperspherical time independent quantum dynamics. Application of the method to the H + CH(4)--> H(2)+ CH(3), H + C(2)H(6)--> H(2)+ C(2)H(5), H + C(3)H(8)--> H(2)+n-C(3)H(7)/H(2)+i-C(3)H(7) and H + CH(3)OH --> H(2)+ CH(3)O/H(2)+ CH(2)OH reactions illustrate the potential of the approach in predicting rate constants, kinetic isotope effects and branching ratios. All studied reactions exhibit large quantum tunneling in the rate constants at lower temperatures. These quantum calculations compare well with the experimental results.
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Affiliation(s)
- Boutheïna Kerkeni
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK OX1 3QZ.
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49
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Hu W, Lendvay G, Troya D, Schatz GC, Camden JP, Bechtel HA, Brown DJA, Martin MR, Zare RN. H + CD4 Abstraction Reaction Dynamics: Product Energy Partitioning. J Phys Chem A 2005; 110:3017-27. [PMID: 16509623 DOI: 10.1021/jp055017o] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper presents experimental and theoretical studies of the product energy partitioning associated with the H + CD4 (nu = 0) --> HD + CD3 reaction for the collision energy range 0.5-3.0 eV. The theoretical results are based on quasiclassical trajectories from (1) first principles direct dynamics calculations (B3LYP/6-31G), (2) an empirical surface developed by Espinosa-García [J. Chem. Phys. 2002, 116, 10664] (EG), and (3) two semiempirical surfaces (MSINDO and reparametrized MSINDO). We find that most of the energy appears in product translation at energies just above the reactive threshold; however, HD vibration and rotation become quite important at energies above 1 eV, each accounting for over 20% of the available energy above 1.5 eV, according to the B3LYP calculations. The barrier on the B3LYP surface, though being later than that on EG, predicts significantly higher HD vibrational excitation than EG. This deviation is contradictory to what would be expected on the basis of the Polanyi rules and derives from modest differences in the potential energy surfaces. The CD3 internal energy is generally quite low, and we present detailed rotational state distributions which show that the CD3 rotational distribution is largely independent of collision energy in the 0.75-1.95 eV range. The most populated rotational levels are N = 5 and 6 on B3LYP, with most of that excitation being associated with motion about the C2 axes, rather than C3 axis, of the CD3 product, in good agreement with the experimental results. Through our extensive studies in this and previous work concerning the scattering dynamics, we conclude that B3LYP/6-31G provides the best available description of the overall dynamics for the title reaction at relatively high collision energies.
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Affiliation(s)
- Wenfang Hu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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50
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Hennig C, Schmatz S. Rotating-Top Approximation in Reduced-Dimensionality Quantum Calculations of Rate Constants: Application to Complex-Forming Nucleophilic Substitution. J Phys Chem A 2005; 110:1524-33. [PMID: 16435813 DOI: 10.1021/jp053521n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Within the framework of reduced-dimensionality quantum scattering theory, we employ Bowman's adiabatic rotation approximation to describe reactive systems that have symmetric-top geometries during the entire collision process. The results are compared with the approach of shifting the total energy by a characteristic rotational energy. Initial state-selected and total thermal rate constants have been computed for the complex-forming gas-phase reaction Cl(-) + CH(3)Cl' --> ClCH(3) + Cl'(-). At room temperature, we find a significant contribution from energetically high vibrational modes. The dependence of the cross-sections on the different angular momenta is analyzed in detail, and high total angular momenta are found to be of considerable importance. The influence of adiabatic azimuthal rotation on the rate constants turns out to be small compared to other effects. In addition, we use a new model to account for the asymmetric modes not explicitly contained in the scattering calculations. The difference to the only available experimental value confirms our conclusion that the Cl-C-Cl' bending modes are of major importance for this reaction.
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Affiliation(s)
- Carsten Hennig
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany
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