Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ta2NiSe5: a candidate topological excitonic insulator with multiple band
  inversions   The electronic structures and topological properties of the orthorhombic and
monoclinic phases of the quasi-one-dimensional excitonic insulator Ta2NiSe5 are
investigated based on density functional theory. In contrast to a single parity
or band inversion across the Fermi level in many topological insulators studied
previously, there are multiple parity and band inversions with or without
spin-orbit coupling in both phases of Ta2NiSe5, resulting in more complex and
topologically nontrivial electronic structures. The Dirac cone type surface
states of the low-temperature monoclinic phase are also obtained. In this
paper, we demonstrate that Ta2NiSe5 is a promising candidate as a
three-dimensional topological excitonic insulator.

37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg