Direct Molecular Dynamics Simulation of Electrocaloric Effect in BaTiO3

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 (30900 K) and external electric fields (0-500 kV/ cm). As expected, a large adiabatic temperature change, Delta T, at the Curie temperature, TC, 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.