Rather, the most probable transition state is one where the rings alternate between an up and down tilt. Try to construct one like this, or a structure which you think is a possible transition state. Conduct a transition state search using the original helicene as the reactant and the possible state as the product. Make sure that you match up these spirals with the proper chirality. Confirm your transition geometry with a frequency search.
Extensions Compare the geometry of the helicenes with the bond length and angles in phenanthene.