Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective inter-band coupling in MgB2 due to anharmonic phonons   We investigate the origin of the inter-band coupling in MgB2 by focusing on
its unusual phononic features, namely, the strong anharmonicity of the phonons
and the presence of both linear and quadratic electron-phonon interactions of
the Su-Schrieffer-Heeger (SSH) type. The bare electronic Hamiltonian has two
bands with intra- and inter-band hopping, which lead to two decoupled
hybridized bands. The phonon Hamiltonian including the anharmonic terms is
diagonalized approximately by a squeezing transformation, which causes the
softening of the phonon frequency. The linear SSH coupling amplitude is
reduced, consistently with the estimates from first-principle calculations.
Additionally, the quadratic coupling generates an effective phonon-induced
interaction between the hybridized bands, which is non-vanishing even in the
limit of vanishing inter-bare-band hopping amplitude.

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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
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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: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
1
The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn