Calculating the dielectric anisotropy of nematic liquid crystals: a reinvestigation of the Maier--Meier theory
Zhang Ran(张然)a)b), He Jun(何军)a)b), Peng Zeng-Hui(彭增辉)a), and Xuan Li(宣丽)a)†
a State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; b Graduate School of Chinese Academy of Sciences, Beijing 100039, China
Abstract This paper investigates the average dielectric permittivity ($\overline{\varepsilon}$) in the Maier--Meier theory for calculating the dielectric anisotropy ($\Delta \varepsilon$) of nematic liquid crystals. For the reason that $\overline{\varepsilon}$ of nematics has the same expression as the dielectric permittivity of the isotropic state, the Onsager equation for isotropic dielectric was used to calculate it. The computed $\overline{\varepsilon}$ shows reasonable agreement with the results of the numerical methods used in the literature. Molecular parameters, such as the polarizability and its anisotropy, the dipole moment and its angle with the molecular long axis, were taken from semi-empirical quantum chemistry (MOCPAC/AM1) modeling. The calculated values of $\Delta \varepsilon$ according to the Maier--Meier equation are in good agreement with the experimental results for the investigated compounds having different core structures and polar substituents.
Received: 19 October 2008
Revised: 24 November 2008
Accepted manuscript online:
Fund: Project supported by
the National Natural Science Foundation of China (Grant Nos 60578035
and 60736042) and the Science Foundation
of Jilin Province of China (Grant Nos 20050520 and 20050321-2).
Cite this article:
Zhang Ran(张然), He Jun(何军), Peng Zeng-Hui(彭增辉), and Xuan Li(宣丽) Calculating the dielectric anisotropy of nematic liquid crystals: a reinvestigation of the Maier--Meier theory 2009 Chin. Phys. B 18 2885
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