Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strain driven onset of non-trivial topological insulating states in
  Zintl Sr$_2X$ compounds ($X$=Pb, Sn)   We explore the topological behavior of the binary Zintl phase of the alkaline
earth metals based compounds Sr$_2$Pb and Sr$_2$Sn using both standard and
hybrid density functional theory. It is found that Sr$_2$Pb lies on the verge
of a topological instability which can be suitably tuned through the
application of a small uniaxial expansion strain ($>$ 3%). The resulting
non-trivial topologically insulating state display well-defined metallic states
in the Sr$_{2}$Pb(010) surface, whose evolution is studied as a function of the
film thickness.

27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom