Biomedical subjects

MP Allen

Publications and source records attributed to MP Allen.

15 recordsLinked to original sources

PubMed2000

Molecular simulation and theory of a liquid crystalline disclination core

Molecular simulations of a nematic liquid crystal confined in cylinder geometry with homeotropic anchoring have been carried out. The core structure of a disclination line defect of strength +1 has been examined, and comparison made with various theoretical treatments, which are presented in a unified way. It is found that excellent fits to the cylindrically symmetrized order tensor profiles may be obtained with appropriate parameter choices; notwithstanding this, on the time scales of the simulation, the cylindrical symmetry of the core is broken and two defects of strength +1 / 2 may be resolved.

Journal Article↗

PubMed2000

Liquid crystal director fluctuations and surface anchoring by molecular simulation

We propose a simple and reliable method to measure the liquid crystal surface anchoring strength by molecular simulation. The method is based on the measurement of the long-range fluctuation modes of the director in confined geometry. As an example, molecular simulations of a liquid crystal in slab geometry between parallel walls with homeotropic anchoring have been carried out using the Monte Carlo technique. By studying different slab thicknesses, we are able to calculate separately the position of the elastic boundary condition and the extrapolation length.

Journal Article↗

PubMed2000

Isotropic-nematic interface of soft spherocylinders

The isotropic-nematic interface of a simple model of liquid-crystal molecules has been investigated using computer simulation, and by numerical minimization of the Onsager free-energy functional. The molecules are represented by long spherocylindrical particles interacting via the Kihara potential. The agreement between simulation and theory is excellent, apart from the bulk coexistence densities which are over estimated by the theory. Planar alignment of the molecules at the interface is preferred in all cases. The number density profile is found to vary monotonically, both in simulation and in theory. Biaxiality of the molecular orientational distribution near the interface is demonstrated.

Journal Article↗

PubMed1996