Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The atomic structure of large-angle grain boundaries $\Sigma 5$ and
  $\Sigma 13$ in ${\rm YBa_2Cu_3O_{7-\delta}}$ and their transport properties   We present the results of a computer simulation of the atomic structures of
large-angle symmetrical tilt grain boundaries (GBs) $\Sigma 5$ (misorientation
angles $\q{36.87}{^{\circ}}$ and $\q{53.13}{^{\circ}}$), $\Sigma 13$
(misorientation angles $\q{22.62}{^{\circ}}$ and $\q{67.38}{^{\circ}}$). The
critical strain level $\epsilon_{crit}$ criterion (phenomenological criterion)
of Chisholm and Pennycook is applied to the computer simulation data to
estimate the thickness of the nonsuperconducting layer ${\rm h_n}$ enveloping
the grain boundaries. The ${\rm h_n}$ is estimated also by a bond-valence-sum
analysis. We propose that the phenomenological criterion is caused by the
change of the bond lengths and valence of atoms in the GB structure on the
atomic level. The macro- and micro- approaches become consistent if the
$\epsilon_{crit}$ is greater than in earlier papers. It is predicted that the
symmetrical tilt GB $\Sigma5$ $\theta = \q{53.13}{^{\circ}}$ should demonstrate
a largest critical current across the boundary.

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The categories of this paper are: plasm-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph