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dc.contributor.authorXing, Lili
dc.contributor.authorBao, Junwei Lucas
dc.contributor.authorWang, Zhandong
dc.contributor.authorWang, Xuetao
dc.contributor.authorTruhlar, Donald G.
dc.date.accessioned2018-12-05T08:04:31Z
dc.date.available2018-12-05T08:04:31Z
dc.date.issued2018-11-23
dc.identifier.citationXing L, Bao JL, Wang Z, wang xuetao, Truhlar DG (2018) Relative rates of hydrogen shift isomerizations depend strongly on multiple-structure anharmonicity. Journal of the American Chemical Society. Available: http://dx.doi.org/10.1021/jacs.8b09381.
dc.identifier.issn0002-7863
dc.identifier.issn1520-5126
dc.identifier.doi10.1021/jacs.8b09381
dc.identifier.urihttp://hdl.handle.net/10754/630174
dc.description.abstractHydroperoxyalkylperoxy species (OOQOOH) are important intermediates that are generated during the autoignition of transport fuels. A key reaction of hydroperoxyalkylperoxy radicals is a [1,5] hydrogen shift, for which kinetics data are experimentally unavailable. Here we study two typical OOQOOH reactions and compare their kinetics to one another and to a previous study to learn the effect of structural variations of the alkyl group on the competition between alternative [1,5] hydrogen shifts of hydroperoxyalkylperoxy species. We use electronic structure calculations to determine previously missing thermochemical data, and we use variational transition state theory (VTST) with multidimensional tunneling (MT), multiple structures, torsional potential anharmonicity, and high-frequency anharmonicity to obtain more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in combustion modeling. The calculated temperature range is 298−1500 K. The roles of various factors in determining the rates are elucidated, and we find an especially strong effect of multiple structure anharmonicity due to torsions. Thus, even though there is some cancellation between the anharmonicity of the reactant and the anharmonicity of the transition state, and even though the reactants are very similar in structure, differing only by a methyl group, the effect of multiple structure anharmonicity has a large effect on the relative rates – as large as a factor of 17 at room temperature and as large as a factor of 7 at 1500 K. This has broad implications for the estimation of reaction rates in many subfields of chemistry, including combustion chemistry and atmospheric chemistry, where rates of reaction of complex molecules are usually estimated without explicit consideration of this fundamental entropic effect. In addition, the pressure-dependence of the rate constants is modelled by system-specific quantum RRK theory.
dc.description.sponsorshipThis work was supported in part by Key Science Foundation of Higher Education of Henan (19A480002), by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award Number DE-SC0015997. The authors are grateful to Feng Zhang for helpful discussions.
dc.publisherAmerican Chemical Society (ACS)
dc.relation.urlhttps://pubs.acs.org/doi/10.1021/jacs.8b09381
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/jacs.8b09381.
dc.subjectAnharmonicity
dc.subjectAutoignition
dc.subjectCombustion
dc.subjectEntropy
dc.subjectHydroperoxyalkylperoxy
dc.subjectKinetics
dc.subjectQuantum chemical calculations
dc.subjectTorsions
dc.titleRelative rates of hydrogen shift isomerizations depend strongly on multiple-structure anharmonicity
dc.typeArticle
dc.contributor.departmentClean Combustion Research Center
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.identifier.journalJournal of the American Chemical Society
dc.eprint.versionPost-print
dc.contributor.institutionEnergy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, China
dc.contributor.institutionDepartment of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minnesota 55455-0431, USA
kaust.personWang, Zhandong
refterms.dateFOA2018-12-05T10:40:43Z
dc.date.published-online2018-11-23
dc.date.published-print2018-12-19


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