Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The impact of hexagonal boron nitride encapsulation on the structural
  and vibrational properties of few layer black phosphorus   The encapsulation of two-dimensional layered materials such as black
phosphorus is of paramount importance for their stability in air. However, the
encapsulation poses several questions, namely, how it affects, via the weak van
der Waals forces, the properties of the black phosphorus and whether these
properties can be tuned on demand. Prompted by these questions, we have
investigated the impact of hexagonal boron nitride encapsulation on the
structural and vibrational properties of few layer black phosphorus, using a
first-principles method in the framework of density functional theory. We
demonstrate that the encapsulation with hexagonal boron nitride imposes biaxial
strain on the black phosphorus material, flattening its puckered structure, by
decreasing the thickness of the layers via the increase of the puckered angle
and the intra-layer P-P bonds. This work exemplifies the evolution of
structural parameters in layered materials after the encapsulation process. We
find that after encapsulation, phosphorene (single layer black phosphorous)
contracts by 1.1% in the armchair direction and stretches by 1.3% in the zigzag
direction, whereas few layer black phosphorus mainly expands by up to 3% in the
armchair direction. However, these relatively small strains induced by the
hexagonal BN, lead to significant changes in the vibrational properties of
black phosphorus, with the redshifts of up to 10 cm$^{-1}$ of the high
frequency optical mode $A_g^1$. In general, structural changes induced by the
encapsulation process open the door to substrate controlled strain engineering
in two-dimensional crystals.

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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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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: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat