Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dielectric, piezoelectric, and elastic properties of BaTiO$_3$/SrTiO$_3$
  ferroelectric superlattices from first principles   The effect of epitaxial strain on the phonon spectra, crystal structure,
spontaneous polarization, dielectric, piezoelectric, and elastic properties of
(001)-oriented ferroelectric (BaTiO$_3$)$_m$/(SrTiO$_3$)$_n$ superlattices ($m
= n = {}$1-4) was studied using the first-principles density-functional theory.
The ground state of free-standing superlattices is the monoclinic $Cm$ polar
phase. Under the in-plane biaxial compressive strain, it transforms to
tetragonal $P4mm$ polar phase, and under the in-plane biaxial tensile strain,
it transforms to orthorhombic $Amm2$ polar phase. When changing the in-plane
lattice parameter, a softening of several optical and acoustic modes appears at
the boundaries between the polar phases, and corresponding components of
dielectric, piezoelectric, and elastic tensors diverge critically. The
comparison of the mixing enthalpy of disordered Ba$_{0.5}$Sr$_{0.5}$TiO$_3$
solid solution modeled using two special quasirandom structures SQS-4 with the
mixing enthalpy of the superlattices reveals a tendency of the
BaTiO$_3$-SrTiO$_3$ system to short-range ordering and shows that these
superlattices are thermodynamically quite stable.

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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
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The categories of this paper are: econ
1
The categories of this paper are: cs
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio