Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single-ion anisotropy in Haldane chains and form factor of the O(3)
  nonlinear sigma model   We consider spin-1 Haldane chains with single-ion anisotropy, which exists in
known Haldane chain materials. We develop a perturbation theory in terms of
anisotropy, where magnon-magnon interaction is important even in the low
temperature limit. The exact two-particle form factor in the O(3) nonlinear
sigma model leads to quantitative predictions on several dynamical properties
including dynamical structure factor and electron spin resonance frequency
shift. These agree very well with numerical results, and with experimental data
on the Haldane chain material Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(PF$_6$).

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The categories of this paper are: alg-geom
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph