Crystallization in Systems of Hard Polyhedra.

[摘要] Hard particle Monte Carlo computer simulations can be used to study both the equilibrium crystal phases of polyhedra and the crystallization pathways in a simplified model system.We present simulations of elongated lithium yttrium fluoride square bipyramids, explain the assembly behavior of gold rhombic dodecahedra, cubes, and octahedra,and investigate in detail the thermodynamics and driving forces for nucleation of a continuous family of polyhedra.In the work on bipyramids we found that either truncation or particle interactions are required to form a novel antiparallel phase.In the study of gold nanopolyhedra we found that the nucleation behavior and structural quality for each polyhedra is strongly dependent on novel properties arising from each shape.Following this, we delved into the nucleation process studying the thermodynamics and free energy barriers to crystallization in rhombic dodecahedra and spheres, and found that the polyhedral faceting stabilized the nucleation pathway.We then demonstrated the importance of this faceting by studying truncations of the rhombic dodecahedra and found that the truncation undermined the local symmetry of the fluid and increased the driving forces required for nucleation.This work demonstrates the role of simulation in understanding experimental systems and how perturbations to shape can alter the pathway to crystallization.

[发布机构] University of Michigan

[效力级别] Crystallization

[关键词] Nucleation;Crystallization;Self-assembly;Monte Carlo Simulation;Colloids;Polyhedra;Chemical Engineering;Engineering;Chemical Engineering