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Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Nov;64(5 Pt 1):051703. Epub 2001 Oct 16.

Microscopic structure and dynamics of a partial bilayer smectic liquid crystal.

Author information

1
Condensed Matter Laboratory, Department of Physics, and Ferroelectric Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.

Abstract

Cyanobiphenyls (nCB's) represent a useful and intensively studied class of mesogens. Many of the peculiar properties of nCB's (e.g., the occurrence of the partial bilayer smectic-A(d) phase) are thought to be a manifestation of short-range antiparallel association of neighboring molecules, resulting from strong dipole-dipole interactions between cyano groups. To test and extend existing models of microscopic ordering in nCB's, we carry out large-scale atomistic simulation studies of the microscopic structure and dynamics of the Sm-A(d) phase of 4-octyl-4'-cyanobiphenyl (8CB). We compute a variety of thermodynamic, structural, and dynamical properties for this material, and make a detailed comparison of our results with experimental measurements in order to validate our molecular model. Semiquantitative agreement with experiment is found: the smectic layer spacing and mass density are well reproduced, translational diffusion constants are similar to experiment, but the orientational ordering of alkyl chains is overestimated. This simulation provides a detailed picture of molecular conformation, smectic layer structure, and intermolecular correlations in Sm-A(d) 8CB, and demonstrates that pronounced short-range antiparallel association of molecules arising from dipole-dipole interactions plays a dominant role in determining the molecular-scale structure of 8CB.

PMID:
11735941
DOI:
10.1103/PhysRevE.64.051703

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