Quasi-mesoscopic model for ferroelectric switching in the chevron geometry

We present a theory of ferroelectric liquid crystal switching which combines elements of standard macroscopic continuum theories with mesoscopic Landau–de Gennes chevron theories. The macroscopic elements of the theory apply in the chevron arms, and are subject to a boundary condition at the chevron interface. This boundary condition can be derived from an anchoring energy associated with the director discontinuity at the chevron tip. The anchoring energy, which corresponds to the degree to which the cone mismatch condition is not satisfied, is calculated using the mesoscopic Landau–de Gennes theory. In the combined theory the frequently used cone-matching condition emerges as a thick cell limit. We are able to calculate a free energy associated with the imposition of a field on particular configurations. There follows a switching phase diagram determining the conditions for thresholdless and bistable switching. We further show that the time dependence of the switching process is determined by the slower bulk relaxation dynamics rather than by the fast chevron surface dynamics.