DESCRIPTION OF VIBRATION-ROTATION ENERGIES OF NONRIGID TRIATOMIC-MOLECULES USING THE GENERATING FUNCTION-METHOD - BENDING STATES AND 2ND TRIAD OF WATER

The generating function method previously developed is applied in this paper for fitting of the bending-rotational levels of the water molecule, where the standard power series expansion of the rotational Hamiltonian has a slow rate of convergence or even diverges. One of the possible extensions of the G-function is considered in some detail. Systematic comparisons are performed with the usual "semirigid model" of centrifugal distortion in asymmetric tops on the basis of least-squares fits to experimental energies. We adjusted the same set of sextic or octic centrifugal distortion parameters to the same experimental data. Standard deviations of fitting and (obs-calc) are typically an order of magnitude better in the generating function method. Extrapolation to higher energy levels is improved as well. © 1992.