Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-principles theory of structural phase transitions for perovskites:
  competing instabilities   We extend our previous first-principles theory for perovskite ferroelectric
phase transitions to treat also antiferrodistortive phase transitions. Our
approach involves construction of a model Hamiltonian from a Taylor expansion,
first-principles calculations to determine expansion parameters, and Monte
Carlo simulations to study the resulting system. We apply this approach to
three cubic perovskite compounds, SrTiO3, CaTiO3, and NaNbO3, that are known to
undergo antiferrodistortive phase transitions. We calculate their transition
sequences and transition temperatures at the experimental lattice constants.
For SrTiO3, we find our results agree well with experiment. For more
complicated compounds like CaTiO3 and NaNbO3, which can have many different
structures with very similar energy, the agreement is somewhat less.

30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph