Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lattice Dynamics of LaFeAsO_{1-x}F_{x} and PrFeAsO_{1-y} via Inelastic
  X-Ray Scattering and First-Principles Calculation   The lattice dynamics of LaFeAsO_{1-x}F_{x} (x=0, 0.1) and PrFeAsO_{1-y}
(y~0.1) are investigated using inelastic x-ray scattering and ab-initio
calculation. Measurements of powder samples provide an approximation to the
phonon DOS, while dispersion is measured from a single crystal of
PrFeAsO_{1-y}. A model that agrees reasonably well with all of the data at room
temperature is built from results of ab-initio calculations by softening the
strength of the Fe-As bond by 30%.

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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: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: chem-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: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: eess