摘要:

Orientational order parameters ⟨P4⟩, ⟨P6⟩ and ⟨P8⟩, as calculated from our X-ray diffraction studies with aligned nematic samples, have been compared with the predictions of Faber's continuum and Maier-Saupe mean-field theories. In contradiction to our previous finding regarding ⟨P2⟩ and ⟨P4⟩, the agreement with Faber's theory is not good. However, experimental inaccuracies and truncation errors during calculations preclude any definite conclusion on this matter.

ISSN:0267-8292    

DOI:10.1080/02678299308027830

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Starting out with mesoscopic orientational balance equations for each orientational component of a liquid crystal which is described as a formal mixture, a set of independent macroscopic variables, the state spaceZ, is induced

ISSN:0267-8292    

DOI:10.1080/02678299308027831

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The theory of dielectric relaxation of uniaxial nematic liquid crystals is developed without recourse to the Fokker–Planck equation by direct averaging of the non-inertial Langevin equation for the rotational brownian motion of the linear molecule in a mean-field nematic potential. The non-inertial equation is regarded as a non-linear Stratonovich stochastic differential equation. The molecular equations for the average values of the dipole moment components so obtained involve both the nematic field and a suddenly applied weak DC measuring field. The equations are linearized in the DC field so that the AC response may be found by linear response theory. The Laplace transform of the equations is closed by a procedure which corresponds exactly to the effective eigenvalue method. It allows one to obtain formulae valid for all barrier heights for the longitudinal τ ∥ and transverse τ ⊥ relaxation times for an arbitrary uniaxial nematic potential in terms of the order parameter. The complex susceptibility induced by a weak AC field applied parallel and perpendicular to the axis of symmetry is also calculated.

ISSN:0267-8292    

DOI:10.1080/02678299308027832

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We present the results of constant pressure molecular dynamics simulation under hydrostatic pressure for soft parallel spherocylinders. A clear first order transition from crystal to smectic phase is observed. The anisotropy of the molecular volume plays an important role in this transition. We study the anisotropy of the diffusion process in the smectic phase by the mean-square displacement in each direction. Also the structures before and after the transition are analysed by means of the pair distribution functions.

ISSN:0267-8292    

DOI:10.1080/02678299308027833

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We have used Landau–de Gennes theory to study anchoring and anchoring transitions at the interface between a nematic liquid crystal and a smooth solid substrate. In contrast to earlier work by Sen and Sullivan, we allow for a spatially varying tilt angle and solve the Euler–Lagrange equations requiring that the order parameters be uniform far from the wall. We have found that temperature-driven anchoring transitions akin to those observed experimentally can be obtained either as a result of the change in the surface order parameter or due to competition between the ordering effects of the solid surface and the nascent isotropic–nematic interface asTNIis approached, in the regime of complete wetting by the isotropic phase. Predictions have also been made for the experimentally observable values of the anchoring energy.

ISSN:0267-8292    

DOI:10.1080/02678299308027834

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0267-8292    

DOI:10.1080/02678299308027799

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor