Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Novel Phase Between Band and Mott Insulators in Two Dimensions   We investigate the ground state phase diagram of the half-filled repulsive
Hubbard model in two dimensions in the presence of a staggered potential
$\Delta$, the so-called ionic Hubbard model, using cluster dynamical mean field
theory. We find that for large Coulomb repulsion, $U\gg \Delta$, the system is
a Mott insulator (MI). For weak to intermediate values of $\Delta$, on
decreasing $U$, the Mott gap closes at a critical value $U_{c1}(\Delta)$ beyond
which a correlated insulating phase with possible bond order (BO) is found.
Further, this phase undergoes a first-order transition to a band insulator (BI)
at $U_{c2}(\Delta)$ with a finite charge gap at the transition. For large
$\Delta$, there is a direct first-order transition from a MI to a BI with a
single metallic point at the phase boundary.

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The categories of this paper are: cmp-lg
2
The categories of this paper are: math
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph