title: Kinetics of the Hydrogen Abstraction from Carbon-3 of 1-Butanol by Hydroperoxyl Radical: Multi-Structural Variational Transition-State Calculations of a Reaction with 262 Conformations of the Transition State.
abstract: We estimated rate constants for the hydrogen abstraction from carbon-3 of 1-butanol by hydroperoxyl radical, a critically important reaction in the combustion of biofuel. We employed the recently developed multi-structural variational transition-state theory (MS-VTST), which utilizes a multifaceted dividing surface that allows us to include the contributions of multiple structures for reacting species and transition states. First, multiconfigurational Shepard interpolation-based on molecular-mechanics-guided interpolation of electronic-structure Hessian data obtained by the M08 HX/jun-cc-pVTZ electronic model chemistry-was used to obtain the portion of the potential energy surface needed for single-structure variational transition-state theory rate constants including multidimensional tunneling; then, the M08-HX/MG3S electronic model chemistry was used to calculate multi-structural torsional anharmonicity factors to complete the MS-VTST rate constant calculations. The lowest-energy structures of the transition state have strongly bent hydrogen bonds. Our results indicate that neglect of multi-structural anharmonicity would lead to errors of factors of 0.3, 46, and 171 at 200, 1000, and 2400 K for this reaction.
authors.affiliation: Department of Chemistry and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors.forename: Prasenjit
authors.initials: P
authors.lastname: Seal
authors.affiliation: Department of Chemistry and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors.forename: Ewa
authors.initials: E
authors.lastname: Papajak
authors.affiliation: Department of Chemistry and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States.
authors.forename: Donald G
authors.initials: DG
authors.lastname: Truhlar
keywords: barrier height; butanol; combustion chemistry; hydrogen abstraction; hydrogen bonds; multi-structural variational transition state theory; torsional anharmonicity