Prediction and Characterization of Barocaloric Effects in Plastic Crystals Using Molecular Dynamics

The energetic challenges of the present times demand the renewal of the technologies that harm the global environment. Amongst them, the scientific efforts towards developing cooling technologies based on the barocaloric effect (BC) present as a promising alternative to the conventional use of greenhouse-effect gases. Materials displaying BC present typically a large entropy change across a first order solid to solid phase transition. Such large entropy difference is usually related to order-disorder phase transitions, as is the case in some plastic crystals such as [CH3NH3]PbI3. There is however a lack of understanding of the atomistic mechanisms driving this effect, which is necessary in order to move towards a feasible solid-state cooling technology. In this work we revise the atomistic origin of the entropy in disordered systems, and present a novel general methodology to calculate the BC estimators by using molecular dynamics NpT simulations using any source of atomistic potential available to the user. We present aswell the application of this method to the analysis of [CH3NH3]PbI3 and LiCB11H12 barocaloric potential.