Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hubbard physics in the symmetric half-filled periodic Anderson-Hubbard
  model   Two very different methods -- exact diagonalization on finite chains and a
variational method -- are used to study the possibility of a metal-insulator
transition in the symmetric half-filled periodic Anderson-Hubbard model. With
this aim we calculate the density of doubly occupied $d$ sites as a function of
various parameters. In the absence of on-site Coulomb interaction ($U_f$)
between $f$ electrons, the two methods yield similar results. The double
occupancy of $d$ levels remains always finite just as in the one-dimensional
Hubbard model. Exact diagonalization on finite chains gives the same result for
finite $U_f$, while the Gutzwiller method leads to a Brinkman-Rice transition
at a critical value ($U_d^c$), which depends on $U_f$ and $V$.

2
The categories of this paper are: math
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph