Coupling between Stretching and Bending Vibration in Nonlinear XY₂ -Type Molecules

In this paper, We study a developed local mode A simple curvilinear internal coordinate Hamiltonian for nonlinear XY₂ molecules is contracted by expending the G-matrix elements and the potential energy function in tems of local coordinates for stretching vibration and normal coordinate for bending vibration, retaining all the important local mode and fermi resonance terms, all the terms higher than 4 order are omitted. The nonlinear least-squares method is used to optimize the potential energy parameters. Vibrational energy levels are calculated based on the fitted results. The caicuiated data agree well with experiment.