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Hernández-Rodríguez J, Sanz-Sanz C, Enríquez PA, González M, Paniagua M. Potential energy surfaces for singlet and triplet states of the LiH 2+ system and quasi-classical trajectory cross sections for H + LiH + and H + + LiH. Phys Chem Chem Phys 2023; 25:28052-28062. [PMID: 37843378 DOI: 10.1039/d3cp02959j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
A new set of six accurate ab initio potential energy surfaces (PESs) is presented for the first three singlet and triplet states of LiH2+ (1,21A', 11A'', 1,23A', and 13A'' states, where four of them are investigated for the first time), which have allowed new detailed studies gaining a global view on this interesting system. These states are relevant for the study of the most important reactions of lithium chemistry in the early universe. More than 45 000 energy points were calculated using the multi-reference configuration interaction level of theory using explicitly correlated methods (ic-MRCI-F12), and the results obtained for each individual electronic state were fitted to an analytical function. Using quasiclassical trajectories and considering the initial diatomic fragment in the ground rovibrational state, we have determined the integral cross sections for the H + LiH+(X2Σ+, C2Π) and H+ + LiH(X1Σ+, B1Π) reactions. In these calculations all available reaction channels were considered: the chemically most important H or H+ transfer/abstraction as well as atom exchange and collision induced dissociation for up to 1.0 eV of collision energy.
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Affiliation(s)
- Javier Hernández-Rodríguez
- Depto. de Química Física Aplicada, Univ. Autónoma de Madrid, Cantoblanco, Spain.
- Depto. de Química Física, Univ. de Salamanca, Spain
| | - Cristina Sanz-Sanz
- Depto. de Química Física Aplicada, Univ. Autónoma de Madrid, Cantoblanco, Spain.
| | | | - Miguel González
- Dept. de Ciència de Materials i Química Física and IQTC, Univ. de Barcelona, Barcelona, Spain.
| | - Miguel Paniagua
- Depto. de Química Física Aplicada, Univ. Autónoma de Madrid, Cantoblanco, Spain.
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Peng Y, Zhang H. Mechanism and Kinetics of Methane Combustion. Part II: Potential Energy Surface for Hydrogen-Abstraction Reaction of CH 4 + O( 3P). J Phys Chem A 2022; 126:1946-1959. [PMID: 35298157 DOI: 10.1021/acs.jpca.1c10860] [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
Methane combustion plays an important role in various fields such as combustion chemistry and atmospheric chemistry of the stratosphere. Highly accurate study of its initial reaction remains a key challenge. Here, through extensive studies with a state-of-the-art ab initio and neural network method, we present a potential energy surface of the O(3P) + CH4 → OH + CH3 reaction on the ground state 13A and the first excited state 23A. In this work, the energies of 10 167 points covering all important regions are obtained with state-averaged complete active space self-consistent field calculations and then fitted using the Levenberg-Marquardt algorithm with a root-mean-square error of 0.391 and 0.442 kcal/mol for the 13A and 23A states, respectively. This study explores the characteristics of the radical van der Waals (VdW) complex and reveals a detailed mechanism of the methane combustion initial reaction. Within the scope of this mechanism, this surface gives a fairly accurate description of the regions around the saddle point, conical intersection, and vdW wells in the entrance for efficient computational simulations. As a theoretical study on a prototypical polyatomic reaction, it is hopeful that this work will modify our understanding of the primary process in hydrocarbon combustion.
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Affiliation(s)
- Ya Peng
- Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R. China
| | - Hui Zhang
- Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R. China
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Purcell SM, Lane PD, D'Andrea L, Elstone NS, Bruce DW, Slattery JM, Smoll EJ, Greaves SJ, Costen ML, Minton TK, McKendrick KG. Surface Structure of Alkyl/Fluoroalkylimidazolium Ionic-Liquid Mixtures. J Phys Chem B 2022; 126:1962-1979. [PMID: 35225614 PMCID: PMC9007465 DOI: 10.1021/acs.jpcb.1c10460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The gas-liquid interface of ionic liquids (ILs) is critically important in many applications, for example, in supported IL phase (SILP) catalysis. Methods to investigate the interfacial structure in these systems will allow their performance to be improved in a rational way. In this study, reactive-atom scattering (RAS), surface tension measurements, and molecular dynamics (MD) simulations were used to study the vacuum interface of mixtures of partially fluorinated and normal alkyl ILs. The underlying aim was to understand whether fluorinated IL ions could be used as additives to modify the surface structure of one of the most widely used families of alkyl ILs. The series of ILs 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][Tf2N]) with n = 4-12 were mixed with a fixed-length, semiperfluorinated analogue (1H,1H,2H,2H-perfluorooctyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8mimF13][Tf2N]), forming [Cnmim](1-x)[C8mimF13]x[Tf2N] mixtures, where x is the bulk mole fraction of the fluorinated component. The RAS-LIF method combined O-atom projectiles with laser-induced fluorescence (LIF) detection of the product OH as a measure of surface exposure of the alkyl chains. For [C8mim](1-x)[C8mimF13]x[Tf2N] mixtures, RAS-LIF OH yields are below those expected from stoichiometry. There are quantitatively consistent negative deviations from linearity of the surface tension. Both results imply that the lower-surface-tension fluoroalkyl material dominates the surface. A similar deficit is found for alkyl chain lengths n = 4, 6, 8, and 12 and for all (nonzero) x investigated by RAS-LIF. Accessible-surface-area (ASA) analyses of the MD simulations for [Cnmim](1-x)[C8mimF13]x[Tf2N] mixtures qualitatively reproduce the same primary effect of fluoro-chain predominance of the surface over most of the range of n. However, there are significant quantitative discrepancies between MD ASA predictions and experiment relating to the strength of any n-dependence of the relative alkyl coverage at fixed x, and on the x-dependence at fixed n. These discrepancies are discussed in the context of detailed examinations of the surface structures predicted in the MD simulations. Potential explanations, beyond experimental artifacts, include inadequacies in the classical force fields used in the MD simulations or the inability of simple ASA algorithms to capture dynamical factors that influence RAS-LIF yields.
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Affiliation(s)
- Simon M Purcell
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Paul D Lane
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Lucía D'Andrea
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Naomi S Elstone
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Duncan W Bruce
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - John M Slattery
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Stuart J Greaves
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Timothy K Minton
- Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
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Kobayashi T, Matsuoka L, Yokoyama K. A quasiclassical trajectory calculation to compute the reaction cross section and thermal rate constant for the cesium exchange reaction 133CsI + 135Cs → 133Cs + I135Cs. COMPUT THEOR CHEM 2019. [DOI: 10.1016/j.comptc.2019.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Peng Y, Jiang Z, Chen J. Mechanism and Kinetics of Methane Combustion, Part I: Thermal Rate Constants for Hydrogen-Abstraction Reaction of CH4 + O(3P). J Phys Chem A 2017; 121:2209-2220. [DOI: 10.1021/acs.jpca.6b12125] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ya Peng
- School of Civil and Resource
Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhong’an Jiang
- School of Civil and Resource
Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jushi Chen
- School of Civil and Resource
Engineering, University of Science and Technology Beijing, Beijing 100083, China
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Zhao H, Wang W, Zhao Y. Thermal Rate Constants for the O( 3P) + CH 4 → OH + CH 3 Reaction: The Effects of Quantum Tunneling and Potential Energy Barrier Shape. J Phys Chem A 2016; 120:7589-7597. [PMID: 27640428 DOI: 10.1021/acs.jpca.6b07029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rate constants and kinetic isotope effects for the O(3P) + CH4 reaction have been investigated with the quantum instanton method in full dimensionality. The calculated rate constants are in good agreement with the experimental values above 400 K, below which the measured values are scattered. Compared to other theoretical approaches, the quantum instanton method predicts the largest quantum tunneling effect, so it gives the largest rate constants at low temperatures. The calculated kinetic isotope effects are always much larger than 1 and increase with decreasing temperature, due to the zero-point energy and quantum tunneling. Our calculations on different potential energy surfaces demonstrate that the potential energy barrier shape dominates the magnitude of quantum tunneling and has a great effect on the kinetic isotope effect.
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Affiliation(s)
- Huali Zhao
- College of Science, Northwest A&F University , Yangling, 712100 Shaanxi Province, P. R. China
| | - Wenji Wang
- College of Science, Northwest A&F University , Yangling, 712100 Shaanxi Province, P. R. China
| | - Yi Zhao
- State Key Laboratory for Physical Chemistry of Solid Surfaces and Fujian Provincial Key Lab of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, P. R. China
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Bonnet L, Corchado JC, Espinosa-Garcia J. Pair-correlated speed distributions for the OH+CH4/CD4 reactions: Further remarks on their classical trajectory calculations in a quantum spirit. CR CHIM 2016. [DOI: 10.1016/j.crci.2016.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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