Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phonon Softening and Direct to Indirect Bandgap Crossover in Strained
  Single Layer MoSe2   Motivated by recent experimental observations of Tongay et al. [Tongay et
al., Nano Letters, 12(11), 5576 (2012)] we show how the electronic properties
and Raman characteristics of single layer MoSe2 are affected by elastic biaxial
strain. We found that with increasing strain: (1) the E' and E" Raman peaks
(E1g and E2g in bulk) exhibit significant red shifts (up to 30 cm-1), (2) the
position of the A1' peak remains at 180 cm-1 (A1g in bulk) and does not change
considerably with further strain, (3) the dispersion of low energy flexural
phonons crosses over from quadratic to linear and (4) the electronic band
structure undergoes a direct to indirect bandgap crossover under 3% biaxial
tensile strain. Thus the application of strain appears to be a promising
approach for a rapid and reversible tuning of the electronic, vibrational and
optical properties of single layer MoSe2 and similar MX2 dichalcogenides.

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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
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The categories of this paper are: stat
29
The categories of this paper are: funct-an
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The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph