Shearing of planar smectic C chevrons

We have theoretically investigated chevron formation in smectic C materials and the transformation of this chevron structure to a tilted layer structu re as the cell is sheared. We find a series of transition temperatures at w hich the behaviour of the cell critically changes. As the cell is cooled fr om the smectic A phase past the first critical temperature there is a secon d order transition which forms two tilted layer states with lower energy th an the smectic A bookshelf structure. Although these low energy tilted stru ctures exist the bookshelf structure is the stable state for zero shear. Ho wever, upon further cooling this bookshelf structure becomes unstable to th e formation of a chevron state. Now when the cell is sheared the chevron st ructure smoothly transforms into the tilted layer structure. As each furthe r critical temperature is passed an additional multiple chevron solution is formed which although a high energy, unstable state may be observed transi ently. For sufficiently lo rv temperatures the transition from chevron to t ilted layer becomes first order. This first order transition occurs as the chevron interface merges with the surface alignment region to form the tilt ed layer structure.