Zeng Sheng-Yuan, Hsu Chih-Hao, Wu Ten-Ming
Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, R.O.C.
J Phys Chem A. 2022 Mar 31;126(12):2018-2030. doi: 10.1021/acs.jpca.1c09527. Epub 2022 Mar 17.
In this paper, we introduced an order parameter, named the local structure similarity (LSS), to measure the resemblance of a cluster structure in a liquid with respect to a perfect crystal. The LSS is based on a dot product of two bond orientational order complex vectors, with one vector associated with a particle in a liquid and the other vector with a particle in a crystal. The calculation of the LSS should scan the entire space of the Euler angles determined by the two coordinate frames describing individually the liquid and the crystal. The effectiveness of the LSS was examined by solid-like clusters in a Lennard-Jones (LJ) system near its liquid-solid phase transition and at solid states below its melting point, where the thermodynamic states of the LJ system were obtained by simulation annealing. The LSS measure was utilized to scrutinize the fcc-like, hcp-like, and bcc-like clusters classified by criteria based on and order parameters. As indicated by our results, the two ways of classification are consistent for fcc-like and hcp-like clusters, which are in a close resemblance to their crystalline counterparts. However, the classification with positive for bcc-like clusters is inconsistent with the results of the LSS measure, which was confirmed by clusters in a LJ system confined between two parallel slabs of particles in the bcc structure arrangement.
在本文中，我们引入了一个序参量，称为局部结构相似性（LSS），以衡量液体中团簇结构与完美晶体的相似程度。LSS基于两个键取向序复矢量的点积，其中一个矢量与液体中的一个粒子相关联，另一个矢量与晶体中的一个粒子相关联。LSS的计算需要扫描由分别描述液体和晶体的两个坐标系所确定的欧拉角的整个空间。通过在Lennard-Jones（LJ）系统中接近其液-固相变处以及低于其熔点的固态下的类固体团簇来检验LSS的有效性，其中LJ系统的热力学状态通过模拟退火获得。LSS度量用于仔细研究根据 和 序参量的标准分类的面心立方（fcc）类、六方密堆积（hcp）类和体心立方（bcc）类团簇。正如我们的结果所示，对于fcc类和hcp类团簇，两种分类方式是一致的，它们与各自的晶体对应物非常相似。然而，对于bcc类团簇，基于正 的分类与LSS度量的结果不一致，这在由处于bcc结构排列的粒子的两个平行平板之间限制的LJ系统中的团簇中得到了证实。
