Cuetos Alejandro, Martínez-Haya Bruno
Departamento de Física Aplicada, Universidad de Almería, 04020 Almería, Spain.
J Chem Phys. 2008 Dec 7;129(21):214706. doi: 10.1063/1.3028539.
The liquid crystal phase diagram of the discotic hard spherocylinder fluid is investigated by Monte Carlo simulations. Thickness-to-diameter aspect ratios within L/D=0.2-0.5 are considered. Three distinct columnar phases are found, namely, a hexatic interdigitated phase (D(hi)), a hexatic ordered phase (D(ho)), both with long-range spatial correlations, and a hexatic disordered phase (D(hd)), in which the columns become fluidlike. Local domains of stacked particles are also observed in the isotropic phase. The stability of the D(ho) and D(hd) phases is favored with increasing anisotropy of the particle shape. As a consequence, the packing fraction versus the aspect ratio representation of the phase diagram features D(ho)-D(hd)-I and D(hi)-D(ho)-I triple points. The study involved the development of an efficient algorithm to compute the shortest distance between two oblate spherocylinder particles. The study provides a general coarse-grain methodology to explore discotic behavior, with fundamental advantages against alternative molecular models.
通过蒙特卡罗模拟研究了盘状硬球柱体流体的液晶相图。考虑了厚度与直径的纵横比在L/D = 0.2 - 0.5范围内的情况。发现了三种不同的柱状相，即具有长程空间相关性的六方叉指相（D(hi)）、六方有序相（D(ho)），以及柱状变得类似流体的六方无序相（D(hd)）。在各向同性相中也观察到了堆叠粒子的局部区域。随着粒子形状各向异性的增加，D(ho)相和D(hd)相的稳定性增强。因此，相图中堆积分数与纵横比的关系图呈现出D(ho)-D(hd)-I和D(hi)-D(ho)-I三相点。该研究涉及开发一种高效算法来计算两个扁球柱体粒子之间的最短距离。该研究提供了一种通用的粗粒度方法来探索盘状行为，相对于其他分子模型具有基本优势。
