We demonstrate that fragility, a technologically relevant characteristic of glass formation, depends on particle shape for glass-formers comprised of hard polyhedral particles. We find that hard polyhedron glass-formers become stronger (less fragile) as particle shape becomes increasingly tetrahedral. We correlate fragility with local structure, and show that stronger systems display a stronger preference for a pairwise face-to-face motif that frustrates global periodic ordering and gives rise in most systems studied to bond angle distributions that are peaked around the ideal tetrahedral bond angle. We demonstrate through mean-field-like simulations of explicit particle pairs and surrounding baths of “ghost” particles that the prevalence of this pairwise configuration can be explained via free volume exchange and emergent entropic force arguments. Our study provides a clear and direct link between the local geometry of fluid structure and the properties of glass formation, independent of interaction potential or other non-geometric tuning parameters. We ultimately demonstrate that the engineering of fragility in colloidal systems via slight changes to particle shape is possible.

中文翻译：

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颗粒形状可调节硬多面体玻璃成型体的脆性

我们证明了脆性，玻璃形成的技术相关特征，取决于由硬多面体颗粒组成的玻璃形成剂的颗粒形状。我们发现，随着颗粒形状越来越四面体，坚硬的多面体玻璃形成剂变得更坚固（更不易碎）。我们将脆弱性与局部结构相关联，并显示出越强的系统对成对的面对面图案表现出更强的偏好，这会挫败整体周期性排序，并且在大多数研究的系统中都出现了围绕理想四面体粘结角达到峰值的粘结角分布。我们证明通过平均场状明确的粒子对模拟和“幽灵”颗粒的周围浴，这种成对配置的患病率可以解释通过自由体积交换和新兴的熵力论证。我们的研究提供了流体结构的局部几何形状与玻璃形成特性之间的清晰直接联系，而与相互作用势或其他非几何调整参数无关。我们最终证明，通过轻微改变颗粒形状，可以在胶体系统中实现易碎性工程。