Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nearest-Neighbor Correlations in Hubbard Model   The Hubbard Hamiltonian is investigated by means of a variational trial wave
function of Gutzwiller's type. The wave function includes nearest - neighbor
correlations in an explicit form. To calculate density matrices the method of
Kikuchi's pseudoensemble is used. The case of half-filled fermionic band
carefully investigated in the limit of a large number of lattice sites. The
ground state energy and correlation functions are determined for lattices with
z=2,4 and 6 nearest neighbors.

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The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org