Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anharmonicity, vibrational instability and Boson peak in glasses   We show that a {\em vibrational instability} of the spectrum of weakly
interacting quasi-local harmonic modes creates the maximum in the inelastic
scattering intensity in glasses, the Boson peak. The instability, limited by
anharmonicity, causes a complete reconstruction of the vibrational density of
states (DOS) below some frequency $\omega_c$, proportional to the strength of
interaction. The DOS of the new {\em harmonic modes} is independent of the
actual value of the anharmonicity. It is a universal function of frequency
depending on a single parameter -- the Boson peak frequency, $\omega_b$ which
is a function of interaction strength. The excess of the DOS over the Debye
value is $\propto\omega^4$ at low frequencies and linear in $\omega$ in the
interval $\omega_b \ll \omega \ll \omega_c$. Our results are in an excellent
agreement with recent experimental studies.

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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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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: adap-org