含氰基混合液晶太赫兹波吸收模拟研究

Simulation study on terahertz absorption of liquid crystal mixture with cyano radical

E7是一种常用的强极性液晶混合物,它具有较高的光学各向异性和较宽的向列相温度范围。本文利用量子化学计算方法,采用基于密度泛函理论的Gaussian98程序包,对构成E7各成分液晶分子在太赫兹波段的吸收进行了研究。基于分子基团对太赫兹波吸收特性,与有关文献的实验数据进行了对比。结果表明,构成分子核心的苯环,分子侧链上的氧原子等,都会对分子吸收强度、吸收峰位置和数目带来较大影响。在实验难以测量的较低太赫兹频段,计算工作仍然能够给出清晰完整的分子振动吸收信息。在较高频率波段,计算得到的分子振动吸收信息与已有的实验数据符合的较好。

E7is a commonly used polar liquid crystal mixture,which has a high optical anisotropy and a wide temperature range of nematic phase.In this work,the absorption characteristics on terahertz band of E7 are studied using the quantum chemistry method,which is called Gaussian98 program based on density functional theory.The terahertz absorption of the constitutional molecular groups were analyzed and compared with the experimental data.The results show that the number of benzene rings and the presence of oxygen atom in the molecular side chain will influence the terahertz absorption strongly in the intensity,the location and number of absorption peaks.Compared with the experimental references,the calculated absorption information of molecular vibration in the lower frequencyband is more clear and complete.In the higher frequency band,the absorption of the calculated molecular vibration is agreement well with the experimental data.