Deformation and orientational order of chiral membranes with free edges
Deformation and orientational order of chiral membranes with free edges
复制标题
具有自由边缘的手性膜的变形和取向顺序
DOI：
10.1039/d1sm00629k
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发表时间：
2021
期刊：
影响因子：
3.4
通讯作者：
Powers, Thomas R.
中科院分区：
文献类型：
--
作者：
Ding, Lijie;Pelcovits, Robert A.;Powers, Thomas R.
受手性棒状病毒组成的胶体膜实验的启发，我们使用蒙特卡罗方法模拟这些系统，并确定棒状病毒的液晶顺序和膜形状的相图。我们将 Lebwohl-Lasher 模型推广到具有手性耦合的向列相，该向列相具有边缘张力和抗弯曲性，并且包括杆相对于局部膜法线倾斜的能量成本。该膜由通过键连接的硬珠组成的三角形网格表示，其中每个珠子都由导向器装饰。珠子可以移动，键可以重新连接，并且董事可以在蒙特卡罗的每个步骤中轮换。当倾斜成本较小时，膜趋于平坦，杆仅在边缘附近扭曲以实现低手性耦合，并保持与膜内部法线平行。在高手性耦合下，棒到处扭曲，形成胆甾状态。当倾斜成本较大时，高手性耦合值下胆甾相的出现伴随着膜弯曲成鞍形。增加边缘张力往往会使膜变平。这些结果说明了由于表面法线无法扭曲而产生的几何挫败感。
Motivated by experiments on colloidal membranes composed of chiral rod-like viruses, we use Monte Carlo methods to simulate these systems and determine the phase diagram for the liquid crystalline order of the rods and the membrane shape. We generalize the Lebwohl–Lasher model for a nematic with a chiral coupling to a curved surface with edge tension and a resistance to bending, and include an energy cost for tilting of the rods relative to the local membrane normal. The membrane is represented by a triangular mesh of hard beads joined by bonds, where each bead is decorated by a director. The beads can move, the bonds can reconnect and the directors can rotate at each Monte Carlo step. When the cost of tilt is small, the membrane tends to be flat, with the rods only twisting near the edge for low chiral coupling, and remaining parallel to the normal in the interior of the membrane. At high chiral coupling, the rods twist everywhere, forming a cholesteric state. When the cost of tilt is large, the emergence of the cholesteric state at high values of the chiral coupling is accompanied by the bending of the membrane into a saddle shape. Increasing the edge tension tends to flatten the membrane. These results illustrate the geometric frustration arising from the inability of a surface normal to have twist.