论文部分内容阅读
在全原子力场模型的基础上,对向列液晶nCB(4-n-alkyl-4′-cyanobiphenyls,n=5—8)进行了等压等温NPT系综下的分子动力学(MD)模拟.对MD的轨迹分析得到了二阶和四阶序参数以及描述液晶分子翻转运动的取向时间相关函数(TCF),并通过一个近似的单指函数对TCF拟合得到了相关时间.在此基础上,计算了nCB(n=5—8)的旋转扩散系数(Rotational diffusion coefficient,RDC).利用基于统计力学模型的Nemtsov-Zakharov方法和Fialkowski方法,分别计算了它们的旋转黏度系数(rotational viscosity coefficient,RVC),进而分别讨论了RVC,RDC和相关时间的奇偶效应.与文献中的实验结果比较表明,该方法得到了合理的计算结果和一致的奇偶效应.
On the basis of the all-atom force field model, molecular dynamics simulations of isothermal NPT ensembles were performed on nCB (n-4-n-alkyl-4’-cyanobiphenyls, n = 5-8) Second-order and fourth-order parameters and the orientation time correlation function (TCF) describing the flip motion of liquid crystal molecules are obtained from the trajectory analysis of MD, and the correlation time is obtained by fitting an approximate one-way function to the TCF , Calculated the Rotational Diffusion Coefficient (RDC) of nCB (n = 5-8). Using the Nemtsov-Zakharov method and the Fialkowski method based on the statistical mechanics model, their rotational viscosity coefficients RVC), and then the odd and even effects of RVC, RDC and related time are discussed separately.Compared with the experimental results in literature, the results show that this method has a reasonable calculation result and a consistent parity effect.