Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Combined Raman scattering and ab initio investigation of
  pressure-induced structural phase transitions in the scintillator ZnWO4   Room-temperature Raman scattering was measured in ZnWO4 up to 45 GPa. We
report the pressure dependence of all the Raman-active phonons of the
low-pressure wolframite phase. As pressure increases new Raman peaks appear at
30.6 GPa due to the onset of a reversible structural phase transition to a
distorted monoclinic b-fergusonite-type phase. The low- and high-pressure
phases coexist from 30.6 GPa to 36.5 GPa. In addition to the Raman measurements
we also report ab initio total-energy and lattice-dynamics calculations for the
two phases. These calculations helped us to determine the crystalline structure
of the high-pressure phase and to assign the observed Raman modes in both the
wolframite and b-fergusonite phases. Based upon the ab initio calculations we
propose the occurrence of a second phase transition at 57.6 GPa from the
b-fergusonite phase to an orthorhombic Cmca phase. The pressure evolution of
the lattice parameters and the atomic positions of wolframite ZnWO4 are also
theoretically calculated and an equation of state reported.

11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys