External field-induced caloric effects in liquid crystals from molecular simulation

Abstract

In the search for alternative, environmentally friendly refrigeration technologies, caloric effects play an important role. Over the past years, liquid crystals have emerged as promising caloric materials. Here, we present a molecular simulation study of the electrocaloric and magnetocaloric effect in liquid crystals exhibiting a nematic–isotropic phase transition. The indirect approach for determining the caloric response is used in combination with molecular dynamics simulations based on the Gay–Berne model. The simulations confirm that the largest response is present at temperatures just above the phase transition and predict the magnitude of the electrocaloric response to be ∼1.6 kJ/kg for an applied electric field of 1600 kV/cm. A much weaker magnetocaloric response is predicted, ∼0.4 kJ/kg for an applied magnetic field of 200 T, indicating that electric fields are much more promising for use in applications than magnetic fields.