Effect of interaction potential on crystal nucleation mechanisms and kinetics for Lennard-Jones-like particles

A major goal of materials science is to understand how molecular-scale interactions impact macroscopic-scale structure and dynamics in materials. Nucleation is an important phase transition phenomenon with relevance in various fields, including biomineralization, pharmaceuticals, and nanotechnology. These phenomena are sensitive to the nature of the molecular interactions between the particles, affecting the energy barrier and pathways of nucleation. We explore the impact of a softened Lennard-Jones potential on crystal nucleation using path sampling techniques and reaction coordinate analyses. Our findings reveal that, although the nucleation rate and reaction coordinate resemble the standard LJ potential, the critical nucleus composition and nucleation pathways differ significantly. The softness of the potential promotes the body-centered cubic (BCC) structure and introduces two distinct nucleation pathways: one dominated by BCC and the other by face-centered cubic (FCC) structures. This insight has implications for modifying size, shape, and surface functionalization in experimental studies of colloids to influence self-assembly. Furthermore, our results provide insights into the ability of controlling polymorph selection based on modulating intermolecular interactions.