  Unusual domains with curved walls and failure to satisfy the
Landau-Lifshitz-Kittel Law are modeled as folding catastrophes (saddle-node
bifurcations). This description of ballistic motion in a viscous medium is
based upon early work by Dawber et al., Appl. Phys. Lett. 82, 436 (2003). It
suggests that ferroelectric films can exhibit folds or vortex patterns but not
both.
