The rovibrational dynamics of a highly excited asymmetric triatomic mo
lecule have been investigated using semiclassical and quantum mechanic
al methods. The rotational energy surface (RES) has been calculated ex
actly from the rigid-bender model of the molecule. The RES topology ha
s been studied and the bifurcation of its critical points has been fou
nd at a certain critical value of the angular momentum. A reorganizati
on of the energy level structure, due to a change of the RES topology,
has been revealed.