Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio lattice thermal conductivity of bulk and thin-film
  $\alpha$-Al$\mathrm{_2}$O$\mathrm{_3}$   The thermal conductivities ($\kappa$) of bulk and thin-film
$\alpha$-Al$_2$O$_3$ are calculated from first principles using both the local
density approximation (LDA), and the generalized gradient approximation (GGA)
to exchange and correlation. The room temperature single crystal LDA value
$\sim39~$W/m$~$K agrees well with the experimental values $\sim35-39~$W/m$~$K,
whereas the GGA values are much smaller $\sim$26$~$W/m$~$K. Throughout the
temperature range, LDA is found to slightly overestimate $\kappa$ whereas GGA
strongly underestimates it. We calculate the $\kappa$ of crystalline
$\alpha$-Al$\mathrm{_2}$O$\mathrm{_3}$ thin films and observe a maximum of
79$\%$ reduction for $10~$nm thickness.

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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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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: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: stat
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The categories of this paper are: bayes-an