Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of morphology on phonons of nanoscopic silver grains   The morphology of nanoscopic Ag grains significantly affects the phonons.
Atomistic simulations show that realistic nanograin models display complex
vibrational properties. (1) Single-crystalline grains. Nearly-pure torsional
and radial phonons appear at low frequencies. For low-energy, faceted models,
the breathing mode and acoustic gap (lowest frequency) are about 10% lower than
predicted by elasticity theory (ET) for a continuum sphere of the same volume.
The sharp edges and the atomic lattice split the ET-acoustic-gap quintet into a
doublet and triplet. The surface protrusions associated with nearly spherical,
high-energy models produce a smaller acoustic gap and a higher vibrational
density of states (DOS) at frequencies \nu<2 THz. (2) Twined icosahedra. In
contrast to the single-crystal case, the inherent strain produce a larger
acoustic gap, while the core atoms yield a DOS tail extending beyond the
highest frequency of single-crystalline grains. (3) Mark's decahedra, in
contrast to (1) and (2), do not have a breathing mode; although twined and
strained, do not exhibit a high-frequency tail in the DOS. (4) Irregular
nanograins. Grain boundaries and surface disorder yield non-degenerate phonon
frequencies, and significantly smaller acoustic gap. Only these nanograins
exhibit a low-frequency \nu^2 DOS in the interval 1-2 THz.

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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: nucl-th
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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: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th