Polymorph selection and nucleation pathway in the crystallization of Hertzian spheres
Polymorph selection and nucleation pathway in the crystallization of Hertzian spheres
复制标题
赫兹球结晶中的多晶型选择和成核途径
DOI：
10.1103/physreve.94.042805
复制
发表时间：
2016
影响因子：
2.4
通讯作者：
Shenghua Xu
中科院分区：
文献类型：
--
作者：
Wenze Ouyang;Cuiliu Fu;Zhiwei Sun;Shenghua Xu
本文用分子动力学方法研究了粒子总数N、压力P和温度T保持不变的NPTenches中赫兹球的结晶过程。已经观察到，键取向顺序，而不是平移顺序（密度）起着主要作用。晶体的多晶型由状态点决定。在小过冷度的条件下，该体系很可能成核成具有亚稳bcc结构的晶体，这可以被视为Alexander-McTague机制的表现。与此相反，小核被发现有一个高度过冷的条件下，面心立方对称性的偏好。预结构的前体，作为种子和润湿的核在成核过程中总是具有高度的bcc样的顺序，尽管不同的状态点。上述结果为理解核软化颗粒的结晶过程提供了线索。
The crystallization process of Hertzian spheres is studied by means of molecular dynamics simulations in anNPTensemble where the total number of particlesN, the pressureP, and the temperatureTare kept constant. It has been observed that the bond orientational ordering rather than the translational ordering (density) plays a primary role. The crystal polymorphs are determined by the state points. Under the conditions of small supercooling, the system is likely to be nucleated into crystals that have a preference for the metastable bcc structure, which can be regarded as a manifestation of the Alexander-McTague mechanism. In contrast, small nuclei are found to have a preference for fcc symmetry under conditions of a high degree of supercooling. Prestructured precursors that act as seeds and wet on the nuclei during nucleation always have a high degree of bcc-like ordering, despite different state points. The results above may provide a clue to the understanding of the crystallization process in core-softened particles.