The field induced switching in antiferro- and ferroelectric smectic C liquid crystals involves the dynamics of a complex 3-dimensional structure. In ferroelectric materials, bistability and hysteresis derive from the substrate surfaces of the device and/or an internal grain boundary, the chevron interface, and in antiferroelectric phases the tristate switching will also be affected by surface conditions and chevron dynamics. Imperfections in smectic layer packing are expected to act as seed points for domain formation in the switching process and, during switching, smectic layers can reorient in either an elastic (reversible) or plastic (irreversible) way. An understanding of all of these effects is of fundamental importance if such materials are going to be fully utilised in optical devices.

To consider such structures and their behaviour we will use modelling which allows for the interaction between order and elasticity in smectic materials and also allows for non-contiguous formation of smectic layers. This latter point is important for modelling the formation of complex structures and will be achieved through the use a tensor approach to model smectic layer structure. This allows a number of interesting effects to be considered: smectic layer melting and defects; plastic layer
reorientation; this approach can also be modified/extended to cover smectic A, ferroelectric and antiferroelectric liquid crystals.

Solutions will be obtained using our own finite difference software and commercial finite element software (FlexPDE, Femlab and possibly VECFEM). The accurate surface energy potentials from Project 2 will be used and by collaborating with Project 4 we will be able to make direct comparisons between the molecular theory
and order-elastic theory. The results of this project will also feed into Project 9 and 10 and be compared to previously obtained experimental results from Profs. Gleeson, Richardson and Crossland.