Molecular rotation based on the minimization of the ro-vibrational Hamilton function

Abstract

Our method of attack of the molecular rotation in the case when the ro-vib interaction can not be considered as a small one involves three steps. Firstly, so called effective classical energy of the molecular rotation is defined as the minimum of the exact classical ro-vib Hamilton function (it is suggested that the dependence of Hamilton function on the angular momentum components is the parametric one). The second step consists in the qualitative analysis of the classical rotational energy function using well known conception of the rotational energy surface (RES). The non- local bifurcation in rotational dynamics of isotopically substituted P 4 molecule is considered as an example. The third step consists in the construction of an effective quantum rotational Hamiltonian from the classical rotational energy function. As an example, the rotational levels of KCN molecule in the ground vibrational state are calculated.