Symmetry in the vibration spectrum of complicated molecule

The vibration spectra of complicated molecule are generally divided into group frequency and ridge frequency. The ridge frequency has a certain symmetry in the vibration spectra of some complicated molecules, such as the ridge frequency of malachite green isothiocyanate (MGITC) molecule which is a molecular probe and has a U(5) symmetry. In this article the U(5) symmetry of molecular vibration spectrum is introduced and tested for its fitting to the low excitation spectrum of MGITC, we find that the theoretical value conforms to the experimental results.