Molecular-Level Insights into the Nucleation Mechanism of One-Component Soft Matter Icosahedral Quasicrystal Studied by Phase-Field Crystal Simulations

The world of fivefold symmetric structures is of great significance for the exploration of the correlation between the symmetry and structure in solid phases. Here, by using the phase-field crystal model, we examine particle-level mechanisms for the formation of one-component soft icosahedral quasicrystals (IQCs) controlled by the interparticle interaction with two length scales. We find that IQCs are nucleated from a modified icosahedral cluster characterized by a unique local structure-bilayer pentagon. The growth of IQCs proceeds through the stacking of bilayer pentagons, combination of modified ICs and modified tetrahedrons, and the mediation between two partially overlapping high symmetric structures by phason flips. Such structural behaviors overcome the geometrical frustration inherent in fivefold symmetries and establish an icosahedral long range order. Our results provide particle-level insights into addressing the long standing problem of how IQC forms and reveal the essential differences in structural behaviors between IQC and glass formations.