Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Local Real-Space View of the Achiral 1$T$-TiSe$_2$ 2 $\times$ 2 $\times$
  2 Charge Density Wave   The transition metal dichalcogenide 1$T$-TiSe$_2$ is a quasi-two-dimensional
layered material undergoing a commensurate 2 $\times$ 2 $\times$ 2 charge
density wave (CDW) transition with a weak periodic lattice distortion (PLD)
below $\approx$ 200 K. Scanning tunneling microscopy (STM) combined with
intentionally introduced interstitial Ti atoms allows to go beyond the usual
spatial resolution of STM and to intimately probe the three-dimensional
character of the PLD. Furthermore, the inversion-symmetric, achiral nature of
the CDW in the $z$-direction is revealed, contradicting the claimed existence
of helical CDW stacking and associated chiral order. This study paves the way
to a simultaneous real-space probing of both charge and structural
reconstructions in CDW compounds.

2
The categories of this paper are: math
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ