...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Physical chemistry chemical physics: PCCP >Twist viscosities and flow alignment of biaxial nematic liquid crystal phases of a soft ellipsoid-string fluid studied by molecular dynamics simulation
【24h】

Twist viscosities and flow alignment of biaxial nematic liquid crystal phases of a soft ellipsoid-string fluid studied by molecular dynamics simulation

机译：分子动力学模拟研究椭圆形弦软流体双轴向列液晶相的扭曲粘度和流动排列

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We have calculated the twist viscosity and the alignment angle between the director and the stream lines in shear flow of a liquid crystal model system, which forms biaxial nematic liquid crystals, as functions of the density, from the Green-Kubo relations by equilibrium molecular dynamics simulation and by a nonequilibrium molecular dynamics algorithm, where a torque conjugate to the director angular velocity is applied to rotate the director. The model system consists of a soft ellipsoid-string fluid where the ellipsoids interact according a repulsive version of the Gay-Berne potential. Four different length-to-width-to-breadth ratios have been studied. On compression, this system forms discotic or calamitic uniaxial nematic phases depending on the dimensions of the molecules, and on further compression a biaxial nematic phase is formed. In the uniaxial nematic phase there is one twist viscosity and one alignment angle. In the biaxial nematic phase there are three twist viscosities and three alignment angles corresponding to the rotation around the various directors and the different alignments of the directors relative to the stream lines, respectively. It is found that the smallest twist viscosity arises by rotation around the director formed by the long axes, the second smallest one arises by rotation around the director formed by the normals of the broadsides, and the largest one by rotation around the remaining director. The first twist viscosity is rather independent of the density whereas the last two ones increase strongly with density. One finds that there is one stable director alignment relative to the streamlines, namely where the director formed by the long axes is almost parallel to the stream lines and where the director formed by the normals of the broadsides is almost parallel to the shear plane. The relative magnitudes of the components of the twist viscosities span a fairly wide interval so this model should be useful for parameterisation experimental data.
机译：我们通过平衡分子动力学的格林-久保关系，计算了液晶模型系统的剪切流中定向粘度和流线之间的扭转粘度和取向角，该液晶模型系统形成了双轴向列型液晶，作为密度的函数。通过非平衡分子动力学算法进行模拟，其中施加与指向矢角速度共轭的转矩来旋转指向矢。模型系统由柔软的椭球串流体组成，其中椭球根据盖伊-伯恩势的排斥形式相互作用。已经研究了四种不同的长宽比。在压缩时，该系统根据分子的尺寸形成盘状或cal裂单轴向列相，并且在进一步压缩时，形成双轴向列相。在单轴向列相中，存在一种扭曲粘度和一种取向角。在双轴向列相中，分别存在三个扭转粘度和三个取向角，分别对应于围绕各种导向器的旋转以及导向器相对于流线的不同对准。发现最小的扭转粘度是由绕长轴形成的指向矢旋转引起的，第二最小的是由绕宽边的法线形成的指向矢旋转引起的，第二最大的黏度是通过绕剩余的指向矢旋转引起的。第一个捻度粘度与密度无关，而后两个捻度则随密度急剧增加。人们发现相对于流线存在一种稳定的指向矢对准，即，由长轴形成的指向矢几乎与流线平行，而由宽边法线形成的指向矢几乎与剪切平面平行。扭曲粘度分量的相对大小跨越相当宽的区间，因此该模型对于参数化实验数据应该是有用的。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号