Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Equilibrium geometries of low-lying isomers of some Li clusters, within
  Hartree-Fock theory plus bond order or MP2 correlation corrections   In a recent study by Kornath et al. [J. Chem. Phys. 118 (2003) 6957], the
Li_n clusters with n=2, 4 and 8 have been isolated in argon matrices at 15 K
and characterized by Raman spectroscopy. This has prompted us to carry out a
theoretical study on such clusters up to n=10, using Hartree-Fock theory, plus
low-order Moeller-Plesset perturbation corrections. To check against the above
study of Kornath et al., as a by-product we have made the same approximations
for n=6 and 8 as we have for n=10. This has led us to emphasize trends with n
through the Li_n clusters for (i) ground-state energy, (ii) HOMO-LUMO energy
gap, (iii) dissociation energy, and (iv) Hartree-Fock eigenvalue sum. The role
of electron correlation in distinguishing between low-lying isomers is plainly
crucial, and will need a combination of experiment and theory to obtain
decisive results such as that of Kornath et al. for Li_8. In particular, it is
shown that Hartree-Fock theory plus bond order correlations does account for
the experimentally observed symmetry T_d symmetry for Li_8.

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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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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: alg-geom
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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: acc-phys