Satoh Katsuhiko
College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan.
J Chem Phys. 2006 Apr 14;124(14):144901. doi: 10.1063/1.2186320.
The influence of an intense external field on the dynamics of the nematic liquid crystal phase is investigated using a molecular dynamics simulation for the Gay-Berne nematogen under isobaric-isothermal conditions. The molecular dynamics as a function of the second-rank orientational order parameter P<2> for a system consisting of a nematic liquid crystal in the presence of an intense magnetic field is compared with that of a similar system without the field. The translational motion of molecules is determined as a function of the translational diffusion coefficient tensor and the anisotropy and compared with the values predicted theoretically. The rotational dynamics of molecules is analyzed using the first- and the second-rank orientational time correlation functions. The translational diffusion coefficient parallel with respect to the director is constrained by the intense field, although the perpendicular one is decreased as the P<2> is increased, just as it is in the system without the field. However, no essential effect of the strong magnetic field is observed in the rotational molecular dynamics. Further, the rotational diffusion coefficient parallel with respect to the director obtained from the first-rank orientational time correlation function in the simulation is qualitatively in agreement with that in the real nematic liquid crystalline molecules. The P<2> dependence of the rotational diffusion coefficient for the system with the intense magnetic field shows a tendency similar to that for the system without the field.
在等压等温条件下，采用分子动力学模拟研究了强外场对向列型液晶相动力学的影响，该模拟针对盖伊 - 伯恩型向列相液晶分子进行。将存在强磁场时由向列型液晶组成的系统的分子动力学作为二阶取向序参量(P_{2})的函数，与无磁场的类似系统进行比较。分子的平动由平动扩散系数张量及其各向异性确定，并与理论预测值进行比较。利用一阶和二阶取向时间关联函数分析分子的转动动力学。尽管与无磁场系统一样，随着(P_{2})增大垂直方向的平动扩散系数减小，但与指向矢平行方向的平动扩散系数受强磁场约束。然而，在分子转动动力学中未观察到强磁场的显著影响。此外，模拟中从一阶取向时间关联函数得到的与指向矢平行方向的转动扩散系数在定性上与实际向列型液晶分子中的情况一致。有强磁场系统的转动扩散系数对(P_{2})的依赖性表现出与无磁场系统类似的趋势。
