Paired correlations of dipolar liquid crystals: A mean-force-potentials approach.

Pair correlations for a polar liquid-crystal (LC) system have been theoretically investigated by means of integral equation approach. Using the dipolar Gay-Berne (GB) interactions between the molecules that composed the LC system, calculations of the nearest-neighbor (NN) and next-NN (NNN) correlators as well as the order parameters and the static dielectric coefficients were performed. It is shown that for a simple cubic packing, NN dipoles tend to be mutually antiparallel with respect to the central dipole, while the opposite trend was observed for NNN dipoles.

Features of director reorientation in a thin nematic film under the influence of crossed electric and magnetic fields.

The theory based on numerical study of the system of hydrodynamic equations, which includes the director motion, shows that under the influence of crossed electric E and magnetic B fields, the director reorients in such a way that the transient quasiperiodic patterns may arise in microsized nematic volumes if the corresponding distortion mode has the fastest response and thus suppresses all other modes, including uniform ones. It has been shown that there is a threshold value of the amplitude of the thermal fluctuations of the director over the microsized nematic film which provides the nonuniform rotation mode rather than the uniform one, whereas the lower values of the amplitude dominate the uniform mode.

Electrically driven torsional distortions in twisted nematic films.

The purpose of this article is to describe the physical mechanism responsible for the appearance of both traveling and nontraveling distortions in a microsized homogeneously aligned nematic (HAN) film under the effect of a large electric field. Numerical studies have been carried out to describe both the traveling and nontraveling dynamic reorientation of the director's field in a thin, in a few tens of micrometers, the HAN film under the effect of a large electric field E (∼1.0V/μm).

Spatially periodic and kinklike distortions in microsized nematic volumes.

The purpose of this article is to describe the physical mechanism responsible for the appearance of both spatially periodic and kinklike distortions in a homogeneously aligned microsized nematic volume under the effect of crossed electric and magnetic fields. Numerical studies were carried out to describe the dynamic reorientation of the director^{'}s field in a thick liquid crystal (LC) cell (∼200μm) under the effect of a large electric field E (∼1.0V/μm) directed at an angle α close to a right angle to magnetic field B (∼7.

Anchoring transition induced by trans-cis isomerization in photosensitive substrate.

A molecular model describing the effective anchoring energy of a liquid crystal (LC) system, composed of 4-n-pentyl-4^{'}-cyanobiphenyl (5CB) molecules deposited on a photosensitive azobenzene layer consisting of 6Az10PVA molecules, is proposed. This model takes into account the interaction between the surface polarization in the LC phase and the surface electric field, arising from the surface charge density. Within the framework of this molecular model, the mechanism responsible for the anchoring transition in the LC phase from homeotropic to planar alignment and vice versa, caused by trans-cis and cis-trans conformational changes in the monolayer 6Az10PVA after laser radiation, is described.

Nanofluidics of nematic liquid crystals in hollow capillaries.

The aim of this paper is to investigate the response of a homogeneously aligned nematic nanosized hollow cavity (HANNHC) confined between two charged horizontal coaxial cylinders and subjected to both a radially applied electrostatic field E, arising from the surface charge density κ and the temperature gradient ∇T set between these cylinders. This was done within the framework of an extension of the classical Ericksen-Leslie theory, supplemented by thermomechanical correction of the shear stress and Rayleigh dissipation function, as well as taking into account the entropy balance equation. The physical mechanism responsible for the excitation of the hydrodynamic flow in the HANNHC is based on the interaction of the director and temperature gradients and the static electric field.

Microfluidics of liquid crystals induced by laser radiation.

Several scenarios for the formation of hydrodynamic flows in microsized hybrid aligned nematic (HAN) channels, based on the appropriate nonlinear extension of the classical Ericksen-Leslie theory, supplemented by thermomechanical correction of the shear stress and Rayleigh dissipation function, as well as taking into account the entropy balance equation, are analyzed. Detailed numerical simulations were performed to elucidate the role of the heat flux q caused by laser radiation focused on the lower boundary of the equally warmed up the HAN channel containing a monolayer of azobenzene with the possibility of a trans-cis and cis-trans conformational changes in formation of the vortex flow v. It is shown that a thermally excited vortex flow is maintained with motion in a positive sense (clockwise) in the vicinity of the orientation defect at the lower boundary of the HAN channel caused by the trans-cis and cis-trans conformational changes.