The bifurcation in the rotational dynamics of triatomic nonsymmetrical hydrides is studied within the framework of microscopic approach. Our method proposed earlier is used for Rotational Energy Surface construction. Critical values of angular momentum for some HDX molecules (X equals O, S, Se, Te, ...) are first calculated.
One of the possible ways to analyze rotational dynamics of molecules in case when the ro-vibrational interaction can not be considered as a small one is discussed in this paper. In the method proposed the most part of the ro-vibrational interaction is taken into account in zero-order approximation. Applied to the number of real molecular ro- vibrational problems, this approach has been proved to be a sufficiently powerful tool for rotational dynamics qualitative analysis and then for revealing rotational multiplet structure. It also can be considered as a base for quantum rotational energy levels calculations.