On the frequency function describing vibrational spectra: N-coupled Morse oscillators

The large-N form of the frequency function describing the density of eigenvalues of a Hamiltonian representing a system of N-coupled Morse oscillators is analyzed. The effect of the values of structural parameters on the function is discussed. The dependence of the frequency function on the dimension of the one-body spectra is considered. Moreover, the influence of the electronic excitation on the frequency function is shown. Then, the frequency function is applied to spectra of the polymeric structure of HgO, a planar sheet of bounded carbon atoms and the AgCN polymer. The frequency function is also used to predict the number of low-lying vibrational levels of SiH4 and 74GeH4 molecules.