Computer Simulation Of Liquid Crystals Research Articles

Molecular simulation of liquid crystals: progress towards a better understanding of bulk structure and the prediction of material properties

This tutorial review covers recent progress in the field of computer simulation of liquid crystals. The development of the main "molecular-based" models for liquid crystals is described. These include lattice models, coarse-grained single site models based on hard and soft interaction potentials, atomistic models and multi-site coarse-grained models. A brief historical review is followed by an assessment of some of the new areas in this field, with an emphasis on understanding of molecular structure in liquid crystal phases and the prediction of bulk material properties. The article also looks to link the field of liquid crystal simulation with important developments in areas such as polymer simulation, lyotropic liquid crystals and model membranes.

Molecular models in computer simulation of liquid crystals

A brief historical survey of progress in computer simulations of liquid crystal phases is provided. We stress the main ideas and developments in the field, concentrating on three different levels of molecular modelling: lattice models, soft nonspherical particles and atomistic models. Emphasis is placed on current state-of-the-art developments including a new parallel molecular dynamics algorithm design for the study of flexible liquid crystals.

Computer simulation of liquid crystals

Computer simulations, using the molecular dynamics and Monte Carlo techniques, and employing simple molecular models, yield insight into general features of phase equilibria, structure, and dynamics of liquid crystals. Here, results are reported from extensive simulations of the Gay - Berne family of molecular models, in which potential parameters are adjusted to vary the molecular length-to-width ratio in a systematic way. Attention is paid to the characterization of nematic, smectic-A and smectic-B phases as functions of these parameters. A simulation study of the approach to the isotropic - nematic phase transition, using a large system size and lengthy runs on the T3D parallel supercomputer, is described. Spatially long-ranged collective orientational correlations develop in the isotropic phase, close to the transition. The direct correlation function has been calculated for these systems, and remains short-ranged, as expected, as the transition is approached. The simulation results are compared with the density functional analysis of isotropic instability relative to the nematic phase.

Phase diagram of a liquid crystal model: A computer simulation study

Continuous potential models used in computer simulation of liquid crystals are reviewed, paying special attention to the anisotropic Gay-Berne model. This potential model, though phenomenological in nature, has a physical background and is able to reproduce mesogenic behaviour. Results from molecular dynamics simulations are presented here showing the different phases appearing in Gay-Berne fluids made up by molecules with axial ratio 3:1. The effect of the attractive forces in stabilizing the orientationally ordered phases is also studied by performing simulations for a WCA-type Gay-Berne fluid. The dynamics of the fluid is examined, especially the process in the vicinity of the isotropic-nematic transition region.

Computer simulation of liquid crystals.

We review recent progress in the computer simulation of liquid crystals, with special emphasis on hard particle models. Surprisingly, the simplest molecular models, taking account only of molecular size and shape, are sufficient to generate a wide variety of liquid crystalline phases, closely analogous to those observed in real life. Thermodynamic stability of different phases is very sensitive to shape, and presumably will also be sensitive to further details of intermolecular interactions as they are incorporated into the model. Realistic atom-atom potential models of liquid crystals are available, but the associated simulations are quite expensive. Thus, while idealized models may be used to study quite general, fundamental properties of mesophases, the modelling of specific liquid crystal systems in a realistic way remains a great challenge. Progress continues to be made on both these fronts.

Molecular Graphics and the Computer Simulation of Liquid Crystals

Abstract Molecular dynamics simulations of systems of hard ellipsoids of revolution have been carried out. Using configurations generated in these simulations, it is shown how molecular graphics can be used to examine the structure within the nematic liquid crystal phase, and close to the isotropic-nematic phase transition. A way of visualizing the degree of orientational order in these systems is presented.