Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universality in the cold and ultracold dynamics of the barrierless
  D$^{+}$+ H$_2$ reaction   We have calculated quantum reactive and elastic cross-sections for D$^{+}+$
para-H$_2$($v$=0, $j$=0) $\rightarrow$ H$^+$ + HD collisons using the
hyperspherical quantum reactive scattering method [Chem. Phys. Lett. 1990,169,
473]. The H$_{3}^{+}$ system is the prototype of barrierless ion-molecule
reactions, apart from its relevance in astrochemistry. The considered collision
energy ranges from the ultracold regime, where only one partial wave is open,
up to the Langevin regime, where many of them contribute. At very low kinetic
energies, both an accurate description of the long-range (LR) region in the
potential energy surface (PES), and long dynamical propagations, up to
distances of 10$^{5}$ a0, are required. Accordingly, calculations have been
carried out on the PES by Velilla et al. [J. Chem. Phys. 2008, 129,084307]
which accurately reproduces the LR interactions. Hyperspherical methodology was
recently modified in order to allow the accurate inclusion of LR interactions
while minimizing the computational expense. Such implementation is shown
particularly suitable for systems involving ions, where the $R^{-4}$ behavior
largely extends the range of the potential. We find a reaction rate coefficient
which remains almost constant in a kinetic energy range of more than ten orders
of magnitude. In particular, the value reached in the Wigner regime, where only
one partial wave is open, is paradoxically the Langevin classical value (within
a few percent) expected at high energies. Results are discussed in terms of
{\em universality} and related to the recently published quantum defect theory
[Phys. Rev. Lett. 2013, 110, 213202]. Since the system has small exothermicity
and a low number of channels, it is possible to test such model in a case where
the loss probability at short range is appreciably far from unity.

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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph