CALCULATION OF THE RAMAN FREQUENCIES AS A FUNCTION OF TEMPERATURE IN PHASE III OF NH4I

摘要

We study here the temperature dependence of the Raman frequencies for the overtone 26 of the librational mode 6 in phase III of NH4I. By using the experimental infrared frequencies of the 26 mode, we predict the Raman frequencies of this overtone 26 mode as a function of temperature at atmospheric pressure in phase III of NH4I. Our calculations indicate that the Raman frequencies of 26 exhibit anomalous behavior at around 110 K (P = 0) in phase III of NH4I, as observed experimentally.