Orientational order in a liquid crystalline mixture studied by molecular dynamics simulation and NMR

Sandström, Dick; Komolkin, Andrei V.; Maliniak, Arnold

doi:10.1063/1.471703

Cited by 35 publications

(14 citation statements)

References 39 publications

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“…There has been extensive experimental [21][22][23][24][25] and theoretical research [12,[26][27][28][29][30][31] on the properties of biphenyl-based nematogens, such as the class of n-alkyl-cyanobiphenyls (nCB), which consist of a central biphenyl core, with a cyano (CN) group at one end, and an N-carbon alkyl chain at the other end of the core ( Figure 1). The properties of the nematic phases, such as transition temperatures and dielectric anisotropy [32], strongly depend on the number of alkyl carbon atoms in the ligand.…”

Section: Resultsmentioning

confidence: 99%

Molecular and Electronic Structure on n-Alkyl Cyanobiphenyl Nematogens

Risser

Ferris

2002

Molecular Crystals and Liquid Crystals

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First principle electronic structure calculations (ab initio and density functional) were performed on a series of substituted cyanobiphenyls to examine the structural and electronic properties as a function of the alkyl tail length and changes in torsion angle about the central bond connecting the rings. We find good agreement between our results and previous electronic structure studies for the optimized torsion angle between phenyls in the cyanobiphenyls, and changes in dipole moment for the cyanobiphenyls. We also find the torsion angle and rotational barriers in cyanobiphenyls to be similar to that in simple biphenyl. However, we find large discrepancies with the recent density functional calculations, which reported a much smaller torsion angle in the cyanobiphenyls.

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Section: Resultsmentioning

confidence: 99%

Molecular and Electronic Structure on n-Alkyl Cyanobiphenyl Nematogens

Risser

Ferris

2002

Molecular Crystals and Liquid Crystals

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“…The full details of the simulation procedure, force field parameters, and data analysis have been described elsewhere. 7 We have also performed a molecular dynamics simulation of neat benzene in the isotropic liquid phase at 300 K.…”

Section: Computational Detailsmentioning

confidence: 99%

“…Palke et al have introduced a computational efficient method to study solutes in a model liquid crystalline solvent by combining the simple Gay-Berne potential with the more elaborate Lennard-Jones site-site potential. 6 Recently, 7 we reported a molecular dynamics ͑MD͒ simulation of a liquid crystalline mixture consisting of benzene and 4-n-pentyl-4Ј-cyanobiphenyl ͑5CB͒. ͑See Fig.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of a liquid crystalline mixture

Sandström

Komolkin

Maliniak

1997

The Journal of Chemical Physics

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We present results from a molecular dynamics simulation of benzene dissolved in the mesogen 4n-pentyl-4Ј-cyanobiphenyl ͑5CB͒. The computer simulation is based on a realistic atom-atom potential and is performed in the nematic phase. Singlet orientational distribution functions are reconstructed from order parameters employing several methods, and the estimated distributions are compared with those obtained directly from the trajectory. Transport properties have been studied by calculating translational diffusion coefficients in directions both parallel and perpendicular to the liquid crystalline director. The simulated diffusion coefficients were found to be of the same order of magnitude as those measured in experiments. Second rank orientational time correlation functions are used to investigate molecular reorientations and significant deviations from the small step rotational diffusion model are established. Molecular structure and internal dynamics of 5CB have been examined by correlating the time dependence of dihedral angles with effective torsional potentials.

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“…The molecular orientational order of LCs has been studied by a number of techniques. More recent experiments, such as fluorescence confocal polarizing microscopy [3], scanning probe microscopy [4], nuclear magnetic resonance (NMR) [5], x-ray diffraction [6], and Fourier transform infrared (FTIR) imaging spectroscopy [7], have enhanced imaging capabilities and furthered our understanding of LC structures and morphology. However, these techniques are not capable of characterizing chemical composition and orientational order for different sample depths.…”

Section: Introductionmentioning

confidence: 99%

Raman Imaging of Nematic and Smectic Liquid Crystals

Büyüktanir

Zhang

Gericke

et al. 2008

Molecular Crystals and Liquid Crystals

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In this article, we demonstrate that confocal Raman microscopy can be utilized to image the director fields of liquid crystal molecules, revealing the spatial patterns of the molecular orientational order both in lateral and axial directions. Here we report on the polarized confocal Raman imaging of the electric field-aligned uniaxial nematic liquid crystal and the in-depth director profiling of the focal conic domains of smectic A liquid crystal. The CN stretching vibrational band [n(CN) ¼ 2228 cm À1 ] and the CÀC stretch of aromatic rings [n(CC) ¼ 1606 cm À1 ] are used to probe the spatial director orientations of 4-pentyl-4 0 -cyanobiphenyl (5CB) and 4-octyl-4 0 -cyanobiphenyl (8CB).

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Orientational order in a liquid crystalline mixture studied by molecular dynamics simulation and NMR

Cited by 35 publications

References 39 publications

Molecular and Electronic Structure on n-Alkyl Cyanobiphenyl Nematogens

Molecular and Electronic Structure on n-Alkyl Cyanobiphenyl Nematogens

Molecular dynamics simulation of a liquid crystalline mixture

Raman Imaging of Nematic and Smectic Liquid Crystals

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