Simplified models for anharmonic numbers and densities of vibrational states. I. Application to NO2 and H3+ Original Research Article

Numbers and densities of vibrational states of non-rotating polyatomic molecules are calculated by a simplified model which accounts for Morse anharmonicities of stretching and for generalized empirical stretch-bend couplings of bending modes. At energies above the dissociation limit, adiabatic channel maxima restrict the molecular phase space. The model is applied to the NO2(X̃ 2A1), NO2(Ã 2B2), and H3+ systems for which satisfactory agreement with the available experimental or calculational results is obtained.