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Gomez-Carrasco S, Felix-Gonzalez D, Aguado A, Roncero O. Spin-orbit transitions in the N +( 3P JA) + H 2 → NH +(X 2 Π, 4Σ -)+ H( 2S) reaction, using adiabatic and mixed quantum-adiabatic statistical approaches. J Chem Phys 2022; 157:084301. [DOI: 10.1063/5.0102376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The cross section and rate constants for the title reaction are calculated for all the spin-orbit states of N+(3PJA) using two statistical approaches, one purely adiabatic and the other one mixing quantum capture for the entrance channel and adiabatic treatment for the products channel. This is made by using a symmetry adapted basis set combining electronic (spin and orbital) and nuclear angular momenta in the reactants channel. To this aim, accurate ab initio calculations are performed separately for reactants and products. In the reactants channel, the three lowest electronic states (without spin-orbit couplings) have been diabatized, and the spin-orbit couplings have been introduced through a model localizing the spin-orbit interactions in the N+ atom, which yields accurate results as compared to ab initio calculations including spin-orbit couplings. For the products, eleven purely adiabatic spin-orbit states have been determined with ab initio calculations. The reactive rate constants thus obtained are in very good agreement with the available experimental data for several ortho-H2 fractions, assuming a thermal initial distribution of spin-orbit states. The rate constants for selected spin-orbit JA states are obtained, to provide a proper validation of the spin-orbit effects to obtain the experimental rate constants.
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Affiliation(s)
| | | | - Alfredo Aguado
- Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Spain
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Garcia E, Jambrina PG, Laganà A. Kinetics Of The H + CH 2 → CH + H 2 Reaction At Low Temperature. J Phys Chem A 2019; 123:7408-7419. [PMID: 31373813 DOI: 10.1021/acs.jpca.9b06212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A quasiclassical trajectory study of the kinetics of the title astrochemical reaction in a range of temperatures varying from 5 to 1000 K (corresponding to both the outer and the inner regions of the protostar and the circumstellar envelopes) was carried out and a clear dependence of the rate coefficient on the temperature is given, in contrast with the constant value adopted in kinetics astrochemical databases. Levering the massive nature of the performed calculations and of the detailed dynamical investigation of the reactive process, a rationalization of the temperature dependence of the released translational energy and of the rovibrational population of the CH and H2 diatomic products is also provided. Furthermore, the effect of the initial rovibrational energy of CH2 on the state-specific rate coefficients and cross sections is analyzed in order to single out the role played by the different regions of the potential energy surface on the dynamical outcomes and on the modeling the temperature dependence of the reactive efficiency of the investigated process. This led to a parametrization of the computed rate in terms of the following double Arrhenius expression (in cm3 s-1), k(T) = 2.50 × 10-10 exp(- 1.67/T) + 5.98 × 10-11 exp(- 280.5/T), alternative to the piecewise formulation into the three subintervals of temperature in which the overall 5-1000 K interval can be divided.
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Affiliation(s)
- Ernesto Garcia
- Departamento de Química Física , Universidad del País Vasco (UPV/EHU) , Paseo de la Universidad 7 , 01006 Vitoria , Spain
| | - Pablo G Jambrina
- Departamento de Química Física , Universidad de Salamanca , Plaza de los Caı́dos , 37008 Salamanca , Spain
| | - Antonio Laganà
- UOS Perugia , CNR ISTM , via Elce di sotto 8 , I-06123 Perugia , Italy.,Master UP srl , Strada Sperandio 15 , I-06125 Perugia , Italy
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Dagdigian PJ. Ab initio potential energy surfaces describing the interaction of CH(X2Π) with H2. J Chem Phys 2016. [DOI: 10.1063/1.4962418] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Paul J. Dagdigian
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
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González M, Mayneris-Perxachs J, Saracibar A, Garcia E. Capture and dissociation in the complex-forming CH(v = 0,1) + D2 → CHD + D, CD2 + H, CD + HD reactions and comparison with CH(v = 0,1) + H2. Phys Chem Chem Phys 2011; 13:13638-44. [PMID: 21698329 DOI: 10.1039/c0cp02483j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rate coefficients for the CH(v = 0,1) + D(2) reaction have been determined for all possible channels (T: 200-1200 K), using the quasiclassical trajectory method and a suitable treatment of the zero point energy. Calculations have also been performed on the CH(v = 1) + H(2) reaction and the CH(v = 1) + D(2) → CH(v = 0) + D(2) process. Most of the results can be understood considering the key role played by the deep minimum of the potential energy surface (PES), the barrierless character of the PES, the energy of the reaction channels, and the kinematics. The good agreement found between theory and experiment for the rate coefficients of the capture process of CH(v = 0) + D(2), the total reactivity of CH(v = 1) + D(2), H(2), as well as the good agreement observed for the related CH(v = 0) + H(2) system (capture and abstraction), gives confidence on the theoretical rate coefficients obtained for the capture processes of CH(v = 1) + D(2), H(2), the individual reactive processes of CH(v = 1) + D(2), H(2), the abstraction and abstraction-exchange reactions for CH(v = 0) + D(2), and the inelastic process mentioned above, for which there are no experimental data available, and that can be useful in combustion chemistry and astrochemistry.
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Affiliation(s)
- Miguel González
- Departament de Química Física i IQTC, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
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González M, Saracibar A, Garcia E. Capture and dissociation in the complex-forming CH + H2 → CH2 + H, CH + H2 reactions. Phys Chem Chem Phys 2011; 13:3421-8. [PMID: 21212873 DOI: 10.1039/c0cp01188f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rate coefficients for the capture process CH + H(2)→ CH(3) and the reactions CH + H(2)→ CH(2) + H (abstraction), CH + H(2) (exchange) have been calculated in the 200-800 K temperature range, using the quasiclassical trajectory (QCT) method and the most recent global potential energy surface. The reactions, which are of interest in combustion and in astrochemistry, proceed via the formation of long-lived CH(3) collision complexes, and the three H atoms become equivalent. QCT rate coefficients for capture are in quite good agreement with experiments. However, an important zero point energy (ZPE) leakage problem occurs in the QCT calculations for the abstraction, exchange and inelastic exit channels. To account for this issue, a pragmatic but accurate approach has been applied, leading to a good agreement with experimental abstraction rate coefficients. Exchange rate coefficients have also been calculated using this approach. Finally, calculations employing QCT capture/phase space theory (PST) models have been carried out, leading to similar values for the abstraction rate coefficients as the QCT and previous quantum mechanical capture/PST methods. This suggests that QCT capture/PST models are a good alternative to the QCT method for this and similar systems.
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Affiliation(s)
- Miguel González
- Departament de Química Física i IQTC, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
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Saracibar A, Goldfield EM, Gray SK. Quantum Mechanical Capture/Phase Space Theory Calculation of the Rate Constants for the Complex-Forming CH + H2 Reaction. J Phys Chem A 2008; 112:12588-96. [DOI: 10.1021/jp805875p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Amaia Saracibar
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, Departamento de Química Física, Universidad del País Vasco 01006, Vitoria, Spain, and Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Evelyn M. Goldfield
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, Departamento de Química Física, Universidad del País Vasco 01006, Vitoria, Spain, and Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Stephen K. Gray
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, Departamento de Química Física, Universidad del País Vasco 01006, Vitoria, Spain, and Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439
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Mayneris J, Sierra JD, González M. Time dependent quantum dynamics study of the Ne+H2+(v=0–4)→NeH++H proton transfer reaction. J Chem Phys 2008; 128:194307. [DOI: 10.1063/1.2917253] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mayneris J, Martínez R, Hernando J, Gray SK, González M. Quantum dynamics study of the K+HF(v=0–2,j=0)→KF+H reaction and comparison with quasiclassical trajectory results. J Chem Phys 2008; 128:144302. [DOI: 10.1063/1.2850887] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Bonnet L. The method of Gaussian weighted trajectories. III. An adiabaticity correction proposal. J Chem Phys 2008; 128:044109. [DOI: 10.1063/1.2827134] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Vasudevan V, Hanson RK, Golden DM, Bowman CT, Davidson DF. High-Temperature Shock Tube Measurements of Methyl Radical Decomposition. J Phys Chem A 2007; 111:4062-72. [PMID: 17388279 DOI: 10.1021/jp0677187] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have studied the two-channel thermal decomposition of methyl radicals in argon, involving the reactions CH3 + Ar --> CH + H2 + Ar (1a) and CH3 + Ar --> CH2 + H + Ar (1b), in shock tube experiments over the 2253-3527 K temperature range, at pressures between 0.7 and 4.2 atm. CH was monitored by continuous-wave, narrow-line-width laser absorption at 431.1311 nm. The collision-broadening coefficient for CH in argon, 2gamma(CH-Ar), was measured via repeated single-frequency experiments in the ethane pyrolysis system behind reflected shock waves. The measured 2gamma(CH-Ar) value and updated spectroscopic and molecular parameters were used to calculate the CH absorption coefficient at 431.1311 nm (23194.80 cm(-1)), which was then used to convert raw traces of fractional transmission to quantitative CH concentration time histories in the methyl decomposition experiments. The rate coefficient of reaction 1a was measured by monitoring CH radicals generated upon shock-heating highly dilute mixtures of ethane, C2H6, or methyl iodide, CH3I, in an argon bath. A detailed chemical kinetic mechanism was used to model the measured CH time histories. Within experimental uncertainty and scatter, no pressure dependence could be discerned in the rate coefficient of reaction 1a in the 0.7-4.2 atm pressure range. A least-squares, two-parameter fit of the current measurements, applicable between 2706 and 3527 K, gives k(1a) (cm(3) mol(-1) s(-1)) = 3.09 x 1015 exp[-40700/T (K)]. The rate coefficient of reaction 1b was determined by shock-heating dilute mixtures of C2H6 or CH3I and excess O2 in argon. During the course of reaction, OH radicals were monitored using the well-characterized R(1)(5) line of the OH A-X (0,0) band at 306.6871 nm (32606.52 cm(-1)). H atoms generated via reaction 1b rapidly react with O2, which is present in excess, forming OH. The OH traces are primarily sensitive to reaction 1b, reaction 9 (H + O2 --> OH + O) and reaction 10 (CH3 + O2 --> products), where the rate coefficients of reactions 9 and 10 are relatively well-established. No pressure dependence could be discerned for reaction 1b between 1.1 and 3.9 atm. A two-parameter, least-squares fit of the current data, valid over the 2253-2975 K temperature range, yields the rate expression k(1b) (cm(3) mol(-1) s(-1)) = 2.24 x 10(15) exp[-41600/T (K)]. Theoretical calculations carried out using a master equation/RRKM analysis fit the measurements reasonably well.
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Affiliation(s)
- Venkatesh Vasudevan
- High Temperature Gasdynamics Laboratory, Mechanical Engineering Department, Stanford University, Stanford, California 94305, USA.
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Martínez R, Sierra JD, Gray SK, González M. Time dependent quantum dynamics study of the O++H2(v=0,j=0)→OH++H ion-molecule reaction and isotopic variants (D2,HD). J Chem Phys 2006; 125:164305. [PMID: 17092071 DOI: 10.1063/1.2359727] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The time dependent real wave packet method using the helicity decoupling approximation was used to calculate the cross section evolution with collision energy (excitation function) of the O++H2(v=0,j=0)-->OH++H reaction and its isotopic variants with D2 and HD, using the best available ab initio analytical potential energy surface. The comparison of the calculated excitation functions with exact quantum results and experimental data showed that the present quantum dynamics approach is a very useful tool for the study of the selected and related systems, in a quite wide collision energy interval (approximately 0.0-1.1 eV), involving a much lower computational cost than the quantum exact methods and without a significant loss of accuracy in the cross sections.
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Affiliation(s)
- Rodrigo Martínez
- Departmento de Química, Universidad de La Rioja, C/Madre de Dios 51, 26006 Logroño, Spain
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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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