  The perovskite crystal BaTiO3 is modeled using a first-principles based
effective Hamiltonian and molecular dynamics simulations are performed to
estimate the pyroelectric response. The electrocaloric temperature change,
\DeltaT, is calculated for different temperatures and externally applied
electric fields. It is found that it is possible to achieve a large \DeltaT,
around 5-6 K, for a relatively small electric field gradient, less than 100
kV/cm, if the applied fields have a small absolute magnitude.
