Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Density Matrix Renormalization Group of Gapless Systems   We investigate convergence of the density matrix renormalization group (DMRG)
in the thermodynamic limit for gapless systems. Although the DMRG correlations
always decay exponentially in the thermodynamic limit, the correlation length
at the DMRG fixed-point scales as $\xi \sim m^{1.3}$, where $m$ is the number
of kept states, indicating the existence of algebraic order for the exact
system. The single-particle excitation spectrum is calculated, using a
Bloch-wave ansatz, and we prove that the Bloch-wave ansatz leads to the
symmetry $E(k)=E(\pi -k)$ for translationally invariant half-integer
spin-systems with local interactions. Finally, we provide a method to compute
overlaps between ground states obtained from different DMRG calculations.

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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph