Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crossover from weakly to strongly correlated regions in the
  two-dimensional Hubbard model -- Off-diagonal wave function Monte Carlo
  studies of Hubbard model II --   The ground state of the two-dimensional (2D) Hubbard model is investigated by
adopting improved wave functions that take into account intersite electron
correlation beyond the Gutzwiller ansatz. The ground-state energy is lowered
considerably, giving the best estimate of the ground-state energy for the 2D
Hubbard model. There is a crossover from weakly to strongly correlated regions
as the on-site Coulomb interaction $U$ increases. The antiferromagnetic
correlation induced by $U$ is reduced for hole doping when $U$ is large, being
greater than the bandwidth, thus increasing the kinetic energy gain. The spin
and charge fluctuations are induced in the strongly correlated region. These
antiferromagnetic and kinetic charge fluctuations induce electron pairings,
which would result in high-temperature superconductivity.

20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph