  Complementary to existing applications of Lagrangian descriptors as an
exploratory method, we use Lagrangian descriptors to find invariant manifolds
in a system where some invariant structures have already been identified. In
this case we use the parametrisation of a periodic orbit to construct a
Lagrangian descriptor that will be locally minimised on its invariant
manifolds. The procedure is applicable (but not limited) to systems with highly
unstable periodic orbits, such as the isokinetic Chesnavich CH4+ model subject
to a Hamiltonian isokinetic theromostat. Aside from its low computational
requirements, the method enables us to study the invariant structures
responsible for roaming in the isokinetic Chesnavich CH4+ model.

Dynamical Systems;Chaotic Dynamics;Chemical Physics