Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological insulator ribbon: Surface states and dynamical response   We study theoretically the distributions of charge and spin polarization of a
topological insulator ribbon, with a realistic rectangular cross section. Due
to constriction in two lateral directions, the surface states discretize into a
series of subbands inside of the bulk band gap. The charge and spin
distribution show interesting characters which are different from an ideal
topological surface state. The effect of merging of four different surface
states into the new one as an entity are analyzed. Optical conductivity and
dynamical spin susceptibility of the ribbon are studied. Different from a
single ideal surface, the optical response and dynamical spin susceptibility of
a ribbon do not have a clear correspondence. The dynamical spin susceptibility
could be used to identify the more adequate model for Bi$_2$Se$_3$.

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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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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: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph