Calculation of rovibrational spectra of water by means of particles-on-concentric-spheres models. I. Ground stretching vibrational state

This is the authors' abstract. We don't add key points for this paper.

A new method is presented to compute bending frequencies and rotational structure in the ground and excited bending states of water-like molecules. As a zeroth-order approximation the water molecule is simulated by the two hydrogens confined to move on a sphere around the oxygen. Even the simplest approximation, choosing the radius of the sphere equal to the equilibrium bond length, gives better results for rotational levels than the rigid bender model does. A further improvement for both bending frequencies and rotational energy levels, especially in excited bending states, has been achieved by introducing an effective radius and an effective mass. These are calculated by averaging over stretching motions to reduce the Schrödinger equation to only the rotational and bending degrees of freedom.