Reaction Rates and Kinetic Isotope Effects of H${}_2$ + OH $\to$ H${}_2$O + H

Abstract

We calculated reaction rate constants including atom tunneling of the reaction of dihydrogen with the hydroxy radical down to a temperature of 50 K. Instanton theory and canonical variational theory with microcanonical optimized multidimensional tunneling (CVT/$\mu$OMT) were applied using a fitted potential energy surface [J. Chem. Phys. 138, 154301 (2013)]. All possible protium/deuterium isotopologues were considered. Atom tunneling increases at about 250 K (200 K for deuterium transfer). Even at 50 K the rate constants of all isotopologues remain in the interval $4\cdot 10^{-20}$ to $4\cdot 10^{-17}$ cm${}^3$ s${}^{-1}$ , demonstrating that even deuterated versions of the title reaction are possibly relevant to astrochemical processes in molecular clouds. The transferred hydrogen atom dominates the kinetic isotope effect at all temperatures.

arXiv commenttitle page, 16 pages, followed by 6 pages of SI

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Cited by in corpus (6)

• Atom Tunneling in the Water Formation Reaction H${}_2$ + OH $\to$ H${}_2$O + H on an Ice Surface
• Instanton Rate Constant Calculations Close to and Above the Crossover Temperature
• Rate constants from instanton theory via a microcanonical approach
• Nonadiabatic instanton rate theory beyond the golden-rule limit
• Warm dust surface chemistry in protoplanetary disks. Formation of phyllosilicates
• The role of atom tunneling in gas-phase reactions in planet-forming disks