Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stone-Wales defects in nitrogen-doped C$_{20}$ fullerenes: Insight from
  $\textit{ab initio}$ calculations   Density functional theory is applied to study the mechanism of the
Stone-Wales defect formation in pure and nitrogen-doped dodecahedral C$_{20}$
fullerenes. The molecular structures of initial and defected cages as well as
transition states dividing them are obtained. Depending on the number of
nitrogen atoms and their relative position in the cage, Stone-Wales defect is
formed through the single additional intermediate state or directly. The
activation energy barrier of the defect formation reduces from 4.93 eV in pure
C$_{20}$ to 2.98 eV in single-doped C$_{19}$N, and reaches $\sim$ 2 eV under
further doping. All nitrogen-doped fullerenes considered possess high kinetic
stability at room temperature. However, they become much less stable at
temperatures of about 750 K that are typical for the fullerene annealing
process.

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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th