Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the phases of Polonium   The thermodynamical properties of the main phases of metallic polonium are
examined using Density Functional Theory. The exceptional nature of the
solid-solid phase transition of $\alpha$ to $\beta$ Po is underlined: it
induces a lowering in symmetry, from cubic to rhombohedral, with increasing
temperature. This is explained as the result of a delicate balance between
relativistic and entropic effects. Overall agreement with existing experimental
data is very good by state-of-the-art standards. The phonons of Po present Kohn
anomalies, and it is shown that the effect of spin-orbit interactions is the
inverse of that in normal metals: due to the non-spherical nature of the Fermi
Surface, spin-orbit effects reduce nesting and harden most phonon frequencies.

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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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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: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio