In this talk I will discuss the benefits of ab initio based molecular dynamics simulations  for the optimization of the electrocaloric effect (ECE). The basic principles of the ECE are now well understood . A further optimization asks for a detailed understanding of the impact of phase transitions as well as atomic, defect and domain structures on the ECE and its reversibility. Simulations allow to isolate these factors and predict design rules for ferroelectric materials and composites with superior cooling responses.
I will focus on the factors giving rise to a large inverse caloric response , in particular phase transitions  and internal bias fields .
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