Fivefold and icosahedral symmetries induced by multiply twinned crystal structures have been studied extensively for their role in influencing the shape of synthetic nanoparticles, and solution chemistry or geometric confinement are widely considered to be essential. Here we report the purely entropy-driven formation of fivefold and icosahedral twinned clusters of particles in molecular simulation without geometric confinement or chemistry. Hard truncated tetrahedra self-assemble into cubic or hexagonal diamond colloidal crystals depending on the amount of edge and vertex truncation. By engineering particle shape to achieve a negligible entropy difference between the two diamond phases, we show that the formation of the multiply twinned clusters is easily induced. The twinned clusters are entropically stabilized within a dense fluid by a strong fluid-crystal interfacial tension arising from strong entropic bonding. Our findings provide a strategy for engineering twinning behavior in colloidal systems with and without explicit bonding elements between particles.

由多重孪晶结构引起的五重和二十面体对称性已被广泛研究，因为它们在影响合成纳米粒子形状方面的作用，溶液化学或几何限制被广泛认为是必不可少的。在这里，我们报告了在没有几何限制或化学的分子模拟中纯熵驱动的五重和二十面体孪生粒子簇的形成。硬截断四面体根据边缘和顶点截断量自组装成立方或六角金刚石胶体晶体。通过设计颗粒形状以实现两个金刚石相之间的熵差可忽略不计，我们表明很容易诱导形成多重孪生簇。孪晶团簇通过强熵键合产生的强流体晶体界面张力在致密流体中熵稳定。我们的研究结果提供了一种在胶体系统中设计孪生行为的策略，有和没有颗粒之间的显式键合元素。