First-principles molecular dynamics modeling of the LiCl-KCl molten salt system

Properties of molten salts are of interest for a wide-range of applications, including nuclear waste partitioning, heat transfer fluids, and synthesis methods. While there has been extensive work showing the value of molecular modeling with interatomic potentials to predict molten salt properties there have been very limited studies of molten salts from a fully first-principles approach. In order to establish optimal approaches and their strengths and limitations in first-principles molten salt modeling, this work provides extensive first-principles molecular dynamics simulations of the LiCl-KCl molten salt system that are validated against existing literature. The basic thermokinetic properties of volume, thermal expansion, bulk modulus, and diffusivity, are calculated for LiCl, KCl and the eutectic LiCl-KCl liquids at multiple temperatures. Convergence testing reveals 216-atom unit cells and simulation times of 6-12 ps are sufficient to provide results with acceptable uncertainties and agreement with experimental data. The results provide a framework of first principles molecular dynamics simulations in the LiCl-KCl molten salt system that can be extended in future research to predict less well-established properties, e.g., the behavior of solutes.