摘要
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.
Based on a full-atomic force field model, molecular dynamics （MD） studies of n CB serials（4-n-alkyl-4＇-cyanobiphenyls, n = 5--8）were performed under the isothermal-isobaric NPT ensemble. The second and forth rank order parameters and the orientational time correlation function （TCF） were obtained by analyzing the trajectory of MD simulation. Then the correlation time was obtained from the fitting of TCF by a single exponential approximation and the rotational diffusion coefficient （RDC） was computed. The rotational viscosity coefficients （RVC） of nCB（ n = 5--8） were calculated by Nemtsov-Zakharov and Fialkowski equations, which are based on the statistical-mechanical approach. The odd-even effect of RVC, RDC and the correlation time were discussed separately. Reasonable agreement between the calculated results and the measured data published in literature is obtained, including identical odd-even effect.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第8期5560-5566,共7页
Acta Physica Sinica
基金
国家自然科学基金(批准号:50703039
60736042)资助的课题~~
关键词
旋转黏度
奇偶效应
分子动力学模拟
向列相液晶
rotational viscosity, odd-even effect, molecular dynamics simulation, nematic liquid crystal
