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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Numerical Analysis Seminars: Computer Simulations of Liquid Crystals

Presented by Mark Wilson (Durham),

5 October 2001 00:00 in CM105

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Liquid crystalline phases typically occur between conventional crystal and liquid phases. Many of the properties they exhibit are intermediate between liquids (e.g. flow properties) and crystalline materials (e.g. anisotropic properties). The coupling between these give rise to many interesting physical phenomena. In particular, electrooptic and magnetooptic effects can occur. Here, changes to an applied electric or magnetic field produce a change in molecular ordering and consequently induce a change in the optical response of the liquid crystal. Such responses have been harnessed in several well-known devices, including the twisted nematic display (TND) (common in everything from mobile phones to laptop computer displays), adaptive optic devices for telescopes, and switchable windows.

This talk describes work carried out into the study of liquid crystalline phases using computer simulation methods. Two well-known techniques have been employed, molecular dynamics and Metropolis Monte Carlo. These methods have been used to simulate the phase behaviour of a range of simple models. The talk will show that simple single-site anisotropic models are sufficient to demonstrate the presence of liquid crystalline phases and that these models can be used to develop methods for predicting key material properties. More sophisticated models, which represent the molecular structure of individual molecules, can also be employed. Although, expensive in terms of computer time, these models can be used to provide an insight into how changes in chemical structure influence phase behaviour and material properties. It is shown that such models can provide a path to "Molecular Engineering", whereby in the future, it may be possible to design molecules that have the desired physical properties, starting only from knowledge of their molecular structure and their interactions.

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Contact David.Bourne@durham.ac.uk for more information