Transformation of the Effective Rotational Hamiltonian of Nonrigid X_2Y Molecules

摘要

The transformation of the effective rotational Hamiltonian H of nonrigid X_2Y molecules to the form having a minimum number of diagonals in the basis of rotational functions of a symmetric top is discussed. Such a transformation is a generalization of the reduction transformation performed for the polynomial effective Hamiltonian H. It is shown that in the general case the transformation substantially changes the form of the initial Hamiltonian, which restricts the region of applicability (J < J_*) of the reduced Hamiltonian represented in a class of elementary functions in terms of angular momentum operators. The values of the rotational quantum number J_* are estimated for the (000) ground and (010) vibrational states of the H_2O molecule.