Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-6 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
Tokyo Tech Academy for Convergence of Materials and Informatics (TAC-MI), Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
J Chem Inf Model. 2020 Jul 27;60(7):3499-3507. doi: 10.1021/acs.jcim.0c00239. Epub 2020 Jul 2.
The molecular dynamics (MD) technique to accelerate simulation of phase transition to liquid-crystalline (LC) phases is demonstrated on the model LC system 4-octyl-4'-cyanobiphenyl (8CB) smectic A phase. Simulation of a phase transition to a smectic phase is challenging because an intrinsically long simulation time and large system size are required owing to the high order and low onset temperature. Acceleration of the simulated transition of 8CB to the smectic A phase was ultimately achieved by selectively weakening the intermolecular Lennard-Jones interaction of alkyl chains and then returning the scaled interaction to the unscaled one. The total time needed to form the smectic A phase using selectively scaled and returned molecular dynamics (ssrMD) was five times shorter than that when using unscaled MD. Formation of the smectic A phase occurred only when induced polarization from the antiparallel dipole dimer point charge was included in the simulation. The use of ssrMD presented herein is anticipated to accelerate the theoretical development of self-assembled organic materials containing both rigid and flexible moieties, including LC materials.
本文展示了分子动力学（MD）技术在模型 LC 体系 4-辛基-4'-氰基联苯（8CB）近晶 A 相的相转变到向列相的模拟中的加速作用。由于高序和低起始温度，模拟相转变到向列相具有挑战性，因为需要固有长的模拟时间和大的系统尺寸。通过选择性地削弱烷基链的分子间 Lennard-Jones 相互作用，然后将缩放后的相互作用返回到未缩放的相互作用，最终实现了对 8CB 向近晶 A 相的模拟转变的加速。使用选择性缩放和返回的分子动力学（ssrMD）形成近晶 A 相所需的总时间比使用未缩放 MD 形成近晶 A 相所需的总时间短五倍。仅当在模拟中包括来自反平行偶极二聚体点电荷的感应极化时，才会形成近晶 A 相。本文中提出的 ssrMD 的使用有望加速包含刚性和柔性部分的自组装有机材料的理论发展，包括 LC 材料。
