The INS spectra of several azines have been analyzed starting from force constant matrix calculated via
and DFT methods. In order to reproduce both vibrational frequencies and intensities, the initial force constants must be fitted until the spectral profile is reproduced. We have checked the various ways which can be followed by the user in this kind of analysis. The choice between scaling or refinement-procedure of the force constants can make an important difference in the reproduction of the INS spectrum.