Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Raman spectrum of 1T'-WTe2 under tensile strain: A first-principles
  prediction   Monolayer WTe2 attracts rapidly growing interests for its large-gap quantum
spin Hall effect,which enables promising apllications in flexible logic
devices. Due to one-dimensional W-W chains,1T'-WTe2 exhibits unique anisotropic
structure and promising properties, which can be modified by simply applying
strains. Based on the first-principles simulations, we show that phonon branch
undergoes soft down to negative frequency at special q points under different
critical strains, i.e., epsilon_a = 11.55 percent along a-axis (with W-W
chains) direction, epsilon_b = 7.0 percent along b-axis direction and
epsilon_ab = 8.44 percent along biaxial direction. Before each critical strain,
the Raman-shift of A1_g, A3_g, and A4_g modes, corresponding to the main peaks
in Raman spectra of 1T'-WTe2 , shows anisotropic response to uniaxial strain
but most sensitive to biaxial strain. Interestingly, we find that the frequency
shift of A3_g mode show parabolic characters of strained 1T'-WTe2, then we
split it into two parts and it shows a Raman-shift transition at about 5
percent strains. While for the A1_g and A4_g modes,the frequencies change
linearly. Through careful structure and vibration analysis, we try to explain
these Raman irregularity in strained 1T'-WTe2.

2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs