Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The phase-diagram of the Blume-Capel-Haldane-Ising spin chain   We consider the one-dimensional spin chain for arbitrary spin $s$ on a
periodic chain with $N$ sites, the generalization of the chain that was studied
by Blume and Capel \cite{bc}: $$H=\sum_{i=1}^N \left(a (S^z_i)^2+ b
S^z_iS^z_{i+1}\right).$$ The Hamiltonian only involves the $z$ component of the
spin thus it is essentially an Ising \cite{Ising} model. The Hamiltonian also
figures exactly as the anisotropic term in the famous model studied by Haldane
\cite{haldane} of the large spin Heisenberg spin chain \cite{bethe}. Therefore
we call the model the Blume-Capel-Haldane-Ising model. Although the Hamiltonian
is trivially diagonal, it is actually not always obvious which eigenstate is
the ground state. In this paper we establish which state is the ground state
for all regions of the parameter space and thus determine the phase diagram of
the model. We observe the existence of solitons-like excitations and we show
that the size of the solitons depends only on the ratio $a/b$ and not on the
number of sites $N$. Therefore the size of the soliton is an intrinsic property
of the soliton not determined by boundary conditions.

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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: q-bio