Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exciton-Peierls mechanism and universal many-body gaps in carbon
  nanotubes   "Metallic" carbon nanotubes exhibit quasiparticle gaps when isolated from a
screening environment. The gap-opening mechanism is expected to be of
electronic origin, but the precise nature is debated. In this work, we show
that hybrid density functional theory predicts a set of excitonic instabilities
capable of opening gaps of the size found in experiment. The excitonic
instabilities are coupled to vibrational modes and, in particular, the modes
associated with the ${\bf \Gamma}-E_{2g}$ and ${\bf K}-A'_1$ Kohn anomalies of
graphene, inducing Peierls lattice distortions with a strong electron-phonon
coupling. In the larger tubes, the longitudinal optical phonon mode becomes a
purely electronic dimerization that is fully symmetry conserving in the zigzag
and chiral tubes, but breaks the symmetry in the armchair tubes. The resulting
gaps are universal (i.e., independent of chirality) and scale as 1/R with tube
radius.

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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
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The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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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: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: math