Systematic Coarse Graining of 4-Cyano-4'-pentylbiphenyl
Systematic Coarse Graining of 4-Cyano-4'-pentylbiphenyl
复制标题
4-氰基-4-戊基联苯的系统粗粒化
DOI：
10.1021/ie901957r
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发表时间：
2011
影响因子：
4.2
通讯作者：
D. Theodorou
中科院分区：
文献类型：
--
作者：
G. Megariotis;Antonia Vyrkou;A. Leygue;D. Theodorou
利用迭代玻尔兹曼反演（IBI）方法，在315 K和1 bar的各向同性相中建立了一个详细的原子模型，推导出了液晶形成分子4-氰-4′-戊基联苯（5CB）的粗粒度模型。粗粒度模型由五个“超原子”组成（一个用于氰基，两个用于联苯部分的芳香环，两个用于烷基尾部），它们被分为三种类型。对IBI进行修改，每次迭代只更新一个有效分子间势（对应于分子间相关函数与原子间相关函数偏差最大的超原子对），证明是实现收敛所必需的。与原子模拟相比，粗粒度模型可以节省35倍的计算成本，用于探索在较低温度下液晶相的排序。发现在288k时产生一阶有序跃迁，具有小的迟滞和可忽略的系统尺寸效应。根据各种结构和动力学测量的详细研究表明，有序相是近晶型而不是实验观察到的向列型。通过对粗粒度模型中分子间有效相互作用势的简单调整，可以使有序温度接近实验值308.5 K。通过放大IBI得到的正反有效相互作用势和尾尾有效相互作用势，可以得到一个向列有序相。
A coarse-grained model is derived for a liquid-crystal-forming molecule, 4-cyano-4′-pentylbiphenyl (5CB), from a detailed atomistic model using the iterative Boltzmann inversion (IBI) method in the isotropic phase at 315 K and 1 bar. The coarse-grained model consists of five “superatoms” (one for the cyano group, two for the aromatic rings in the biphenyl moiety, and two for the alkyl tail), which are categorized as three types. A modification of IBI, wherein only one of the effective intermolecular potentials (the one corresponding to the superatom pair whose intermolecular correlation function exhibits the highest deviation from the atomistic one) is updated at each iteration, proves to be necessary to achieve convergence. The coarse-grained model, which enables a savings of a factor of 35 in computational cost relative to atomistic simulation, is used to explore ordering into liquid-crystalline phases at lower temperatures. It is found to yield a first-order ordering transition at 288 K with small hysteresis and negligible system size effects. A detailed investigation in terms of various structural and dynamical measurements indicates that the ordered phase is of the smectic type rather than nematic, as observed experimentally. The ordering temperature can be brought close to the experimental value of 308.5 K through the simple rescaling of the intermolecular effective interaction potentials employed in the coarse-grained model. A nematic ordered phase can be obtained from the coarse-grained model by scaling up the head-head and tail-tail effective interaction potentials obtained by IBI.
影响因子：
3.9
作者：
Brake, JM;Daschner, MK;Abbott, NL
通讯作者：
Abbott, NL