  The electrocaloric effect (ECE) in BaTiO3 is simulated using two different
first-principles based effective Hamiltonian molecular dynamics methods. The
calculations are performed for a wide range of temperatures (30--900 K) and
external electric fields (0--500 kV/cm). As expected, a large adiabatic
temperature change, Delta-T, at the Curie temperature, T_C, is observed. It is
found that for single crystals of pure BaTiO3, the temperature range where a
large Delta-T is observed is narrow for small external electric fields (<50
kV/cm). Large fields (>100 kV/cm) may be required to broaden the effective
temperature range. The effect of crystal anisotropy on the ECE Delta-T is also
investigated. It is found that applying an external electric field along the
[001] direction has a larger ECE than those along the [110] and [111]
directions.
