Uncertainty quantification in the ab initio rate-coefficient calculation for the CH3CH(OH)CH3 + OH → CH3C•(OH)CH3 + H2O reaction

Theoretical methods to obtain rate coefficients are essential to fundamental combustion chemistry research, yet the associated uncertainties are largely unexplored in a systematic manner. In this paper we focus on the study of parametric uncertainties for a hydrogen-atom-abstraction reaction, CH3CH(OH)CH3 + OH -> CH3C center dot(OH)CH3 + H2O, which bears significant importance in low-temperature alcohol combustion and especially in autoignition models. After identifying the parameters causing significant uncertainty in the rate-coefficient calculations, Bayesian inference is employed to determine the joint probability density function (PDF) thereof using the experimental data of Dunlop and Tully (1993) [6] on isopropanol + OH. The inferred PDFs are compared to the various parameter values obtained from high-level electronic-structure calculations in order to assess the limitations of current methodologies. To gain insight on modeling the kinetic isotope effect (KIE), the reaction of the hydroxyl radical with deuterated isopropanol is also investigated. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.