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Ab initio characterization of the potential energy profiles for the multi-channel reactions: H/Cl + CH3OH. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Lu D, Behler J, Li J. Accurate Global Potential Energy Surfaces for the H + CH3OH Reaction by Neural Network Fitting with Permutation Invariance. J Phys Chem A 2020; 124:5737-5745. [DOI: 10.1021/acs.jpca.0c04182] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dandan Lu
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, China
- Institut für Physikalische Chemie, Theoretische Chemie, Universität Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
| | - Jörg Behler
- Institut für Physikalische Chemie, Theoretische Chemie, Universität Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
| | - Jun Li
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, China
- Institut für Physikalische Chemie, Theoretische Chemie, Universität Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
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Shan X, Sambrook MR, Clary DC. Calculations on the unimolecular decomposition of the nerve agent VX. Phys Chem Chem Phys 2020; 22:564-574. [PMID: 31845698 DOI: 10.1039/c9cp05109k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It is very difficult to perform experiments on the physical parameters for the thermal decomposition of chemical nerve agents such as VX and computations, therefore, are useful. The reaction dynamics of the gas-phase pericyclic hydrogen transfer of the nerve agent VX is studied computationally. The geometries of the stationary structures are calculated at M06-2X/jul-cc-pVTZ level of theory. Single point energy calculations are carried out at the CBS/QB3 level to correct the energy barriers. Canonical reaction rate constants are calculated as a function of temperature. The one-dimensional semiclassical transition state theory is used to analyse the quantum tunneling effects. A reduced-dimensional hindered rotor model is proposed, tested, and applied to calculate the vibrational partition functions. It is found that the ester (O-side) and thioester (S-side) side chains of VX undergo pericyclic H-transfer reactions that result in decomposition of the molecule. The S-side reaction is favoured both kinetically and thermodynamically and dominates the pyrolysis over the temperature range from 600 K to 1000 K. It is predicted that VX completely decomposes in 2 s at temperatures above 750 K.
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Affiliation(s)
- Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.
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Kerkeni B, Bacchus-Montabonel MC, Shan X, Bromley ST. Understanding H 2 Formation on Hydroxylated Pyroxene Nanoclusters: Ab Initio Study of the Reaction Energetics and Kinetics. J Phys Chem A 2019; 123:9282-9291. [PMID: 31584814 DOI: 10.1021/acs.jpca.9b06713] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rate constants of H2 formation on five models of silicate nanoclusters with varying degrees of hydroxylation, (Mg4Si4O12)(H2O)N, were computed over a wide temperature range [180-2000 K]. We tested nine combinations of density functional methods and basis sets for their suitability for calculating reaction energies and barrier heights, and we computed the minimum energy H + H → H2 reaction paths on each nanocluster. Subsequently, we computed the rate constants employing three semiclassical approaches that take into account tunneling and nonclassical reflection effects by means of the zero curvature tunneling (ZCT), the small curvature tunneling (SCT), and the one-dimensional semiclassical transition state theory (SCTST) methods, which all provided comparable results. Our investigations show that the H2 formation process following the Langmuir-Hinshelwood (LH) mechanism is more efficient on the hydroxylated (N = 1-4) nanoclusters than on the bare (N = 0) one due to relatively higher reaction barrier height on the latter. H2 formation is found to have the smallest barrier and the most exothermic reaction for the moderately hydroxylated (Mg4Si4O12)(H2O)2 nanocluster for all nine considered methods. Overall, we conclude that all the considered nanoclusters are very efficient catalyzing grains for H2 formation in the physical conditions of the interstellar medium (ISM) with pyroxene nanosilicates having moderate to high hydroxylation being more efficient than bare nanograins.
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Affiliation(s)
- Boutheïna Kerkeni
- Département de Physique, Laboratoire de Physique de la Matière Condensée (LPMC) Faculté des Sciences de Tunis , Université de Tunis El Manar , Campus Universitaire, 2092 , Tunis , Tunisia.,Institut Supérieur des Arts Multimédia de la Manouba , Université de la Manouba , 2010 , la Manouba , Tunisia.,Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA , F-92195 Meudon , France.,Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière , Villeurbanne cedex 69622 , France
| | | | - Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry , University of Oxford , South Parks Road , Oxford OX1 3QZ , United Kingdom
| | - Stefan T Bromley
- Departament de Ciencia de Materiales i Química Física & Institut de Química Teorica i Computacional , Universitat de Barcelona , Barcelona 08028 , Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA) , Barcelona 08010 , Spain
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Cooper AM, Kästner J. Low-Temperature Kinetic Isotope Effects in CH3OH + H → CH2OH + H2 Shed Light on the Deuteration of Methanol in Space. J Phys Chem A 2019; 123:9061-9068. [DOI: 10.1021/acs.jpca.9b07013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- April M. Cooper
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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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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Shan X, Sambrook MR, Clary DC. Theoretical Study of Gas-Phase Unimolecular Decomposition of Simulants of the Nerve Agent VX. J Phys Chem A 2019; 123:59-72. [PMID: 30511567 DOI: 10.1021/acs.jpca.8b10416] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In order to further understand and support approaches for the degradation and destruction of toxic chemicals, the thermal decomposition of the nerve agent VX through possible pericyclic hydrogen transfer reactions is investigated using simulant molecules. A total of four simulant molecules are studied. Three of them have only one possible H-transfer site, while the other has two. They are chosen to bring physical insights into individual steps of the pericyclic reaction mechanism as well as the possible existence of competing mechanisms. The unimolecular reaction rate constants at the high-pressure limit are calculated. Geometries of stationary structures on the potential energy surfaces are calculated with the MP2 method as well as the B3LYP and M06-2X functionals and 6-311++G(d,p), jul-cc-pVTZ, and aug-cc-pVTZ basis sets. The barrier heights are corrected using energy values obtained at the CBS/QB3 level of theory. The contribution of the quantum tunneling effect to the reaction rate constants is included using one-dimensional semiclassical transition state theory. Adiabatic barrier heights, reaction rate constants, and branching ratio of the competing mechanisms are reported.
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Affiliation(s)
- Xiao Shan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry , University of Oxford , South Parks Road , Oxford OX1 3QZ , United Kingdom
| | - Mark R Sambrook
- CBR Division, Defence Science and Technology Laboratory (Dstl) , Porton Down , Salisbury SP4 OJQ , 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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Stace AJ, Clary DC. Modern theoretical chemistry: the legacy of Prof. John N. Murrell. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0460. [PMID: 29431685 PMCID: PMC5805920 DOI: 10.1098/rsta.2017.0460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/13/2017] [Indexed: 06/08/2023]
Affiliation(s)
- Anthony J Stace
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - David C Clary
- Department of Physical and Theoretical Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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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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