Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Splitting between Bright and Dark excitons in Transition Metal
  Dichalcogenide Monolayers   The optical properties of transition metal dichalcogenide monolayers such as
the two-dimensional semiconductors MoS$_2$ and WSe$_2$ are dominated by
excitons, Coulomb bound electron-hole pairs. The light emission yield depends
on whether the electron-hole transitions are optically allowed (bright) or
forbidden (dark). By solving the Bethe Salpeter Equation on top of $GW$ wave
functions in density functional theory calculations, we determine the sign and
amplitude of the splitting between bright and dark exciton states. We evaluate
the influence of the spin-orbit coupling on the optical spectra and clearly
demonstrate the strong impact of the intra-valley Coulomb exchange term on the
dark-bright exciton fine structure splitting.

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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: math
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int