Phonon dispersion in polyinosinic acid.

A study of the normal modes of vibration and their dispersion in polyinosinic acid [poly (I)] along the helix axis based on Urey-Bradley force field is reported. It leads to a better interpretation of Raman and FTIR spectra. A comparison of dispersion curves of poly (I) with poly (G) has been made. Characteristic features of dispersion curves, such as regions of high density-of-states, repulsion and character mixing are discussed. Predictive value of heat capacity as a function of temperature is reported.