Free Energy of Ferroelectric Liquid Crystals

Recalling the free-energy expression for the nonferroelectric SmC liquid crystals discussed in the preceding section, one should not be too surprised to find that the free 

The elastic part of the free energy is analogous to the chiral nematic phase. It has been derived by Nakagawa et al. and can be expressed as follows  

Using the geometry shown in the Figiue 4.16, the director axis ft becomes 

The dielectric interaction energy density is simply given by y . For an applied electric field along they axis, for example, in the plane of the smectic layer, the interaction energy is given by 

As in the other phases of liquid crystals, the free energy associated with the surface interaction is the most complicated one. It takes on further significance in the case of surface-stabilized ferroelectric liquid crystals. These surface interactions have been studied by various workers In their treatments the surface energy is expressed as 

---