Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Optimal Inhomogeneity for Superconductivity: Finite Size Studies   We report the results of exact diagonalization studies of Hubbard models on a
$4\times 4$ square lattice with periodic boundary conditions and various
degrees and patterns of inhomogeneity, which are represented by inequivalent
hopping integrals $t$ and $t^{\prime}$. We focus primarily on two patterns, the
checkerboard and the striped cases, for a large range of values of the on-site
repulsion $U$ and doped hole concentration, $x$. We present evidence that
superconductivity is strongest for $U$ of order the bandwidth, and intermediate
inhomogeneity, $0 <t^\prime< t$. The maximum value of the ``pair-binding
energy'' we have found with purely repulsive interactions is $\Delta_{pb} =
0.32t$ for the checkerboard Hubbard model with $U=8t$ and $t^\prime = 0.5t$.
Moreover, for near optimal values, our results are insensitive to changes in
boundary conditions, suggesting that the correlation length is sufficiently
short that finite size effects are already unimportant.

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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th