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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 (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.