Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ground States of Heisenberg Spin Clusters from Projected Hartree-Fock
  Theory   We apply Projected Hartree-Fock theory (PHF) for approximating ground states
of Heisenberg spin clusters. Spin-rotational, point-group and
complex-conjugation symmetry are variationally restored from a broken-symmetry
mean-field reference, where the latter corresponds to a product of local spin
states. A fermionic formulation of the Heisenberg model furnishes a conceptual
connection to PHF applications in quantum chemistry and detailed equations for
a self-consistent field optimization of the reference state are provided.
Different PHF variants are benchmarked for ground-state energies and spin-pair
correlation functions of antiferromagnetic spin rings and three different
polyhedra, with various values of the local spin-quantum number s. The low
computational cost and the compact wave-function representation make PHF a
promising complement to existing approaches for ground states of molecular spin
clusters, particularly for large s and moderately large N. The present work may
also motivate future explorations of more accurate post-PHF methods for
Heisenberg spin clusters.

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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th