  Specific forms of the exchange correlation energy functionals in
first-principles density functional theory-based calculations, such as the
local density approximation (LDA) and generalized-gradient approximations
(GGA), give rise to structural lattice parameters with typical errors of -2%
and 2%. Due to a strong coupling between structure and polarization, the order
parameter of ferroelectric transitions, they result in large errors in
estimation of temperature dependent ferroelectric structural transition
properties. Here, we employ a recently developed GGA functional of Wu and Cohen
[Phys. Rev. B 73, 235116 (2006)] and determine total-energy surfaces for
zone-center distortions of BaTiO3, PbTiO3, and SrTiO3, and compare them with
the ones obtained with calculations based on standard LDA and GGA. Confirming
that the Wu and Cohen functional allows better estimation of structural
properties at 0 K, we determine a new set of parameters defining the effective
Hamiltonian for ferroelectric transition in BaTiO3. Using the new set of
parameters, we perform molecular-dynamics (MD) simulations under effective
pressures p=0.0 GPa, p=-2.0 GPa, and p=-0.005T GPa. The simulations under
p=-0.005T GPa, which is for simulating thermal expansion, show a clear
improvement in the cubic to tetragonal transition temperature and c/a parameter
of its ferroelectric tetragonal phase, while the description of transitions at
lower temperatures to orthorhombic and rhombohedral phases is marginally
improved. Our findings augur well for use of Wu-Cohen functional in studies of
ferroelectrics at nano-scale, particularly in the form of epitaxial films where
the properties depend crucially on the lattice mismatch.
