论文标题
硬盘固定在列明针中：基于粒子的液晶中胶体相互作用的模拟
Chaining of hard disks in nematic needles: particle-based simulation of colloidal interactions in liquid crystals
论文作者
论文摘要
悬浮在液晶中的胶体颗粒可以表现出各种有效的各向异性相互作用，这些相互作用可以在自组装过程中调整和使用。我们模拟了悬浮在密集的硬针中溶液中的硬盘的二维系统，作为悬浮在列明溶裂性液体晶体中的胶体系统的模型系统。新型的事件链蒙特卡洛技术使我们能够直接在密集的列相的显式液晶颗粒中直接测量微观模拟中的胶体相互作用。我们找到了沿导演的磁盘的定向短距离吸引力，该磁盘触发与导演平行的链接，并且似乎与标准的液晶场理论相矛盾，而标准的四极吸引力的结果则与优选的$ {45^{\ circ}} $角度相矛盾。我们的结果可以通过短距密度依赖性的耗竭相互作用来解释，该相互作用已被忽略。耗尽相互作用的方向性和强度是由硬杆的平面锚定弱引起的。如果磁盘接近，则耗尽的吸引力在四极弹性吸引力上稳健地占主导地位。许多磁盘的自组装通过中间链条进行，这表明在溶裂性液晶胶体中，耗尽相互作用在结构形成过程中起重要作用。
Colloidal particles suspended in liquid crystals can exhibit various effective anisotropic interactions that can be tuned and utilized in self-assembly processes. We simulate a two-dimensional system of hard disks suspended in a solution of dense hard needles as a model system for colloids suspended in a nematic lyotropic liquid crystal. The novel event-chain Monte Carlo technique enables us to directly measure colloidal interactions in a microscopic simulation with explicit liquid crystal particles in the dense nematic phase. We find a directional short-range attraction for disks along the director, which triggers chaining parallel to the director and seemingly contradicts the standard liquid crystal field theory result of a quadrupolar attraction with a preferred ${45^{\circ}}$ angle. Our results can be explained by a short-range density-dependent depletion interaction, which has been neglected so far. Directionality and strength of the depletion interaction are caused by the weak planar anchoring of hard rods. The depletion attraction robustly dominates over the quadrupolar elastic attraction if disks come close. Self-assembly of many disks proceeds via intermediate chaining, which demonstrates that in lyotropic liquid crystal colloids depletion interactions play an important role in structure formation processes.
