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The terahertz (THz) spectrum absorptions of nematic liquid crystal (LC) material, i.e. N-(p-methoxybenzylidene)-p-butylaniline (MBBA), and its relevant compounds are simulated in this paper by using the density functional theory (DFT) method. A strong absorptive frequency is located at 3.65 THz for the MBBA, which is in agreement with experimental data found in the literature. The result suggests that the DFT method is effective for dealing with the anisotropic nematic LC compounds. [ABSTRACT FROM AUTHOR]

Temperature dependence of ratio between dielectric anisotropy and order parameter of fluorinated nematic liquid crystal is investigated by using a semi-empirical molecular orbital package that can accurately calculate an angle between molecular dipole moment and long axis. We optimize the molecular conformations with three semi-empirical Hamiltonians AM1, PM3 and PM5, and then make a comparison between computational results and experimental measurements. It is shown that the results obtained from AM1 method are in good agreement with the measurements. The present study offers an applicable method to predict the dielectric properties of liquid crystal material. [ABSTRACT FROM AUTHOR]

This paper reports that the equilibrium structure of NH2 has been optimized at the QCISD/6-311++G (3df, 3pd) level. The ground-state NH2 has a bent (C2v, X2B1) structure with an angle of 103.0582°. The geometrical structure is in good agreement with the other calculational and experimental results. The harmonic frequencies and the force constants have also been calculated. Based on the group theory and the principle of microscopic reversibility, the dissociation limits of NH2(C2v, X2B1) have been derived. The potential energy surface of NH2(X2B1) is reasonable. The contour lines are constructed, the structure and energy of NH2 reappear on the potential energy surface. [ABSTRACT FROM AUTHOR]

Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interfacial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solid-fluid interfacial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners. [ABSTRACT FROM AUTHOR]