Electroclinic effect in chiral smectic liquid crystal

4 Electroclinic effect in chiral smectic liquid crystal 

As shown in Section 4.3.2, when the tilt angle is 6, the spontaneous polarization Ps is 

The tilt angle as a function of the applied electric field E can be found by minimizing the free energy  

When the applied field is low, the tilt angle is small, and the cubic term in Equation (4.53) can be neglected. The tilt angle is 

The induced tilt angle is linearly proportional to the applied field. The tilt angle can be larger than 10° at the electric field of 10 V/pm for some liquid crystals. 

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