Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model*

In this work, we show that a binary system interacting through Lennard-Jones (LJ) potential predicts all phases reported in experiments in which nanoparticles are effectively described as quasi hard spheres. Furthermore, we show that binary lattices may be described as combinations of a small number of particle clusters, motifs, which generalize the four Z-N that describe Frank Kasper phases. We report a phase diagram consisting of 53 equilibrium phases, whose stability is quite insensitive to the microscopic details of the potentials, thus giving raise to some universality. Our results show that meta-stable phases share the same motifs as equilibrium phases. Connections with packing models, phase diagrams with repulsive potentials and the prediction of new superlattices in experiments are thoroughly discussed.