Simulations of some physical parameters of homologous series of nBT and nCHBT at 0.3–20.0 THz

ABSTRACT

In this work, the terahertz (THz) absorption of homologous series of isothiocyanobiphenyls (nBT) and 4-(trans-4ʹ-n-alkylcyclohexyl)isothiocyanato-benzene (nCHBT) are simulated by using the density functional theory (DFT) method. Numerical results show that absorption of the tested nematic liquid crystals (NLCs) varies up to 0.04 in the broad range of 0.3–20.0 THz and takes maximum value in the range of 9–14 THz.

In addition, the values of molecular polarisabilities (α_o, α_e) increase with the increase in the number of carbon atoms in the alkyl chain, while refractive indices (n_o, n_e) decreases. The calculated birefringence (Δn) values for nCHBT are approximately twice as large as the birefringence value for nBT. It is crucial to examine these series of nematic liquid crystals at THz frequencies due to the role of soft matter in various switchable THz components.

Graphical Abstract

KEYWORDS:

• Numerical calculations
• terahertz radiation
• nematic liquid crystals
• refractive index
• birefringence

Acknowledgments

This research was supported partially by the project RMN/08-836/2018/WAT and by the Polish Ministry of Sciences and Higher Education under grant Iuventus Plus no. 0365/IP2/2016/74, entitled ‘Tunable properties of metamaterial transducers with short response times in the THz range’.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the RMN [RMN/08-836/2018/WAT];Iuventus Plus [0365/IP2/2016/74].