Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reaction Rates and Kinetic Isotope Effects of H$_2$ + OH $\rightarrow$
  H$_2$O + H   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.

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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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The categories of this paper are: math
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int