  Recent experiments have found a bent-core liquid crystal in which the layer
chirality alternates from layer to layer, giving a racemic or "antichiral"
material, even though the molecules are uniformly chiral. To explain this
effect, we map the liquid crystal onto an Ising model, analogous to a model for
chiral order in polymers. We calculate the phase diagram for this model, and
show that it has a second-order phase transition between antichiral order and
homogeneous chiral order. We discuss how this transition can be studied by
further chemical synthesis or by doping experiments.
