Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Merging Dirac points and topological phase transitions in the
  tight-binding model on the generalized honeycomb lattice   Moving, merging and annihilating Dirac points are studied theoretically in
the tight-binding model on honeycomb lattice with up-to third-nearest-neighbor
hoppings. We obtain a rich phase diagram of the topological phase transitions
in the parameter space of direction-dependent hoppings. We obtain the
conditions for the three Dirac points to merge and for the tricritical points.
We find that only very small third-nearest-neighbor hoppings are enough for the
existence of the merging of three-Dirac-points and the tricritical points, if
the system is sufficiently anisotropic. The density of states is obtained to be
$D(\epsilon) \propto |\epsilon|^{1/3}$ when three Dirac points merge, and
$D(\epsilon) \propto |\epsilon|^{1/4}$ at the tricritical points. It is
possible to realize these topological phase transitions in the ultracold atoms
on the optical lattice, strained monolayer graphene or strained bilayer
graphene.

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The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci