Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical renormalization-group study of spin correlations in
  one-dimensional random spin chains   We calculate the ground-state two-spin correlation functions of spin-1/2
quantum Heisenberg chains with random exchange couplings using the real-space
renormalization group scheme. We extend the conventional scheme to take account
of the contribution of local higher multiplet excitations in each decimation
step. This extended scheme can provide highly accurate numerical data for large
systems. The random average of staggered spin correlations of the chains with
random antiferromagnetic (AF) couplings shows algebraic decay like $1/r^2$,
which verifies the Fisher's analytic results. For chains with random
ferromagnetic (FM) and AF couplings, the random average of generalized
staggered correlations is found to decay more slowly than a power-law, in the
form close to $1/\ln(r)$. The difference between the distribution functions of
the spin correlations of the random AF chains and of the random FM-AF chains is
also discussed.

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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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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: nucl-th
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The categories of this paper are: econ
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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: atom-ph
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The categories of this paper are: quant-ph
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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: math
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex