Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-principles studies of the local structure and relaxor behavior of
  Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$-PbTiO$_3$-derived ferroelectric perovskite
  solid solutions   We have investigated the effect of transition metal dopants on the local
structure of the prototypical 0.75 Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$-0.25 PbTiO$_3$
relaxor ferroelectric. We find that these dopants give rise to very different
local structure and other physical properties. For example, when Mg is
partially substituted by Cu or Zn, the displacement of Cu or Zn is much larger
than that of Mg, and is even comparable to that of Nb. The polarization of
these systems is also increased, especially for the Cu-doped solution, due to
the large polarizability of Cu and Zn. As a result, the predicted maximum
dielectric constant temperatures ($T_m$) are increased. On the other hand, the
replacement of a Ti atom with a Mo or Tc dramatically decreases the
displacements of the cations and the polarization, and thus, the $T_m$ values
are also substantially decreased. The higher $T_m$ cannot be explained by the
conventional argument based on the ionic radii of the cations. Furthermore, we
find that Cu, Mo, or Tc doping increase the cations displacement disorder. The
effect of the dopants on the temperature dispersion ${\Delta}T_m$, which is the
change of $T_m$ for different frequencies, is also discussed. Our findings lay
the foundation for further investigations of unexplored dopants.

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The categories of this paper are: quant-ph
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The categories of this paper are: alg-geom
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: physics
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat