An Atomic Cluster Expansion interatomic potential for lithium: investigating the solid and liquid phases
We develop an atomic cluster expansion (ACE) interatomic potential for lithium that accurately models both the solid and liquid phase and the corresponding melting point. The predicted properties for both phases are in close agreement with density functional theory (DFT) and experimental data from literature. The potential is able to capture the energy differences of the different competing phases of the solid at 0 K. It also predicts temperature dependent liquid density, viscosity, and diffusion coefficient. The melting point is calculated using the two-phase coexistence method. By using the ACE formalism, we also systematically investigate the contributions of different N-body interactions and the number of radial parameters needed to separately represent both phases, thereby shedding light on the complexity of the ACE potential needed to model solid and liquid lithium efficiently.