  In this paper, we analyse the phase space structure of the roaming dynamics
in a two degree of freedom potential energy surface consisting of two identical
planar Morse potentials separated by a distance. This potential energy surface
was previously studied in [1], and it has two potential wells surrounded by an
unbounded flat region containing no critical points. We study the phase space
mechanism for the transference between the wells using the method of Lagrangian
descriptors.
