Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometrical frustration effects on charge-driven quantum phase
  transitions   The interplay of Coulomb repulsion and geometrical frustration on
charge-driven quantum phase transitions is explored. The ground state phase
diagram of an extended Hubbard model on an anisotropic triangular lattice
relevant to quarter-filled layered organic materials contains homogeneous
metal, 'pinball' and three-fold charge ordered metallic phases. The stability
of the 'pinball' phase occurring for strong Coulomb repulsions is found to be
strongly influenced by geometrical frustration. A comparison with a spinless
model reproduces the transition from the homogeneous metallic phase to a
pinball liquid, which indicates that the spin correlations should play a much
smaller role than the charge correlations in the metallic phase close to the
charge ordering transition. Spin degeneracy is, however, essential to describe
the dependence of the system on geometrical frustration. Based on finite
temperature Lanczos diagonalization we find that the effective Fermi
temperature scale, T*, of the homogeneous metal vanishes at the quantum phase
transition to the ordered metallic phase driven by the Coulomb repulsion. Above
this temperature scale 'bad' metallic behavior is found which is robust against
geometrical frustration in general. Quantum critical phenomena are not found
whenever nesting of the Fermi surface is strong, possibly indicating a first
order transition instead. 'Reentrant' behavior in the phase diagram is
encountered whenever the 2kF-CDW instability competes with the Coulomb driven
three-fold charge order transition. The relevance of our results to the family
of quarter-filled materials: theta-(BEDT-TTF)2X is discussed.

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The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
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The categories of this paper are: eess
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph