Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: [Ag(NH3)2]2SO4: A coordination strategy on the cationic-moiety to design
  nonlinear optical materials   Over decades, guided by the anionic group theory, the majority work has been
focused on the anionic-moiety of a nonlinear optical material, however, the
property guided structure modification and design on the cationic-moiety has
long been neglected. Herein, we report for the first time a coordination
strategy on the cationic-moiety, as demonstrated by the first exmple,
[Ag(NH3)2]2SO4 vs Ag2SO4, the coordination of the plus one Ag+ cation by the
neutral ligand forming the [Ag(NH3)2]+ cationic-moiety drives the formation of
the noncentrosymmetric tetragonal P-421c structure which exhibits a remarkable
property improvement, including a strong SHG intersity (1.4*KDP vs 0 @1064 nm),
and a large birefringence (delta(n)cal.: 0.102 vs 0.012 @1064 nm). Furthermore,
we discover that owing to the strong hydrogen bonds and spatial confinement of
[SO4]2- anions, the cation [Ag(NH3)2]+ bends parallel to the crystallographic c
axis with a bond angle of N-Ag-N = 174.35deg, generating a permenant dipole
moment z = -0.12 D that is responsible for the large birefringence that
enlarges the range of the phase matching SHG laser output. We believe what we
discover is only a glimpse of the long been neglected crystal engineering on
the cationic-moiety. Encourage by this work, exciting works on other ionic
compound systems shall flood in.

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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: physics
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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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: hep-ex