Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-principles theory of ferroelectric phase transitions for
  perovskites: The case of BaTiO3   We carry out a completely first-principles study of the ferroelectric phase
transitions in BaTiO$_3$. Our approach takes advantage of two features of these
transitions: the structural changes are small, and only low-energy distortions
are important. Based on these observations, we make systematically improvable
approximations which enable the parameterization of the complicated energy
surface. The parameters are determined from first-principles total-energy
calculations using ultra-soft pseudopotentials and a preconditioned
conjugate-gradient scheme. The resulting effective Hamiltonian is then solved
by Monte Carlo simulation. The calculated phase sequence, transition
temperatures, latent heats, and spontaneous polarizations are all in good
agreement with experiment. We find the transitions to be intermediate between
order-disorder and displacive character. We find all three phase transitions to
be of first order. The roles of different interactions are discussed.

23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph