Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computational study of (111) epitaxially strained ferroelectric
  perovskites BaTiO3 and PbTiO3   The phase transition behaviour of PbTiO3 and BaTiO3 under (111) epitaxial
strain is investigated using density-functional theory calculations. From
tensile strains of +0.015 to compressive strains of -0.015, PbTiO3 undergoes
phase transitions from C2 through two Cm phases and then to R3m. The total
polarisation is found to be almost independent of strain. For the same range of
strains BaTiO3 undergoes phase transitions from a single Cm phase, through R3m
and then to R-3m. In this case the application of compressive strain inhibits
and then completely suppresses the polarisation on transition to the non-polar
R-3m phase.

29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol