Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vibrational and thermodynamic properties of high-pressure phases in
  LiYF_4   Possible variations in the dynamical behaviour of LiYF$_{4}$ due to its
structural changes following several pressure-induced phase transitions are
examined by making use of the complementary techniques of quasi-harmonic
lattice dynamics and molecular dynamics simulation. The phonon spectra in the
entire Brillouin zone and the respective Gibbs free energies are calculated for
the three high-pressure polymorphs of LiYF$_{4}$ that are stable at T = 0, with
an aim to understand their relative stabilities as functions of pressure and
temperature in terms of volume compression and vibrational entropy. Molecular
dynamics simulations provide qualitative impressions about a temperature-driven
second-order transformation and also of kinetic effects in the subsequent
pressure-driven first-order phase transition. In addition, the calculations
predict anomalous thermal expansion at low temperature in phases I and IIa
while irreversibilty of phase II $\to$ phase III transition on subsequent
pressure release.

28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an