Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of Intrinsic Vibrational Gap Modes in Three-Dimensional Ionic
  Crystals   The existence of anharmonic localization of lattice vibrations in a perfect
3-D diatomic ionic crystal is established for the rigid-ion model by molecular
dynamics simulations. For a realistic set of NaI potential parameters, an
intrinsic localized gap mode vibrating in the [111] direction is observed for
fcc and zinc blende lattices. An axial elastic distortion is an integral
feature of this mode which forms more readily for the zinc blende than for the
fcc structure. Molecular dynamics simulations verify that in each structure
this localized mode may be stable for at least 200 cycles.

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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex