Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tetragonal to orthorhombic phase transition in SmFeAsO: a synchrotron
  powder diffraction investigation   The crystal structure of SmFeAsO has been investigated by means of Rietveld
refinement of high resolution synchrotron powder diffraction data collected at
300 K and 100 K. The compound crystallizes in the tetragonal P4/nmm space group
at 300 K and in the orthorhombic Cmma space group at 100 K; attempts to refine
the low temperature data in the monoclinic P112/n space group diverged. On the
basis of both resistive and magnetic analyses the tetragonal to orthorhombic
phase transition can be located at T about 140 K.

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The categories of this paper are: quant-ph
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The categories of this paper are: gr-qc
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
2
The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: stat