Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magneto-elastic instability in Molecular Antiferromagnetic Rings   Lattice stability in a model of antiferromagnetic ring coupled to adiabatic
phonons is investigated for different values of the spin and numbers of
magnetic sites. The magneto-elastic transition is shown to be heavily affected
by the spin value, displaying a qualitative difference in the nature of the
instability for spin one-half. Among the different synthesized materials,
Cu$_8$ seems to be the best candidate to observe lattice dimerization in these
systems. Our analysis excludes stable lattice distortions in higher spin rings.
The effects of thermal fluctuations are studied in the Cu$_8$ model, where a
characteristic crossover temperature is estimated.

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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
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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: nlin
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The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
2
The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex