Pippard relations modified by the Raman frequency shifts for the phases I and II in NH4I

Pippard relations in terms of the frequency shifts of the v(7) (40 cm(-1)) lattice mode, are established here for the phases I and II in NH4I. The temperature-induced frequency shift, (1/v)(partial derivative v/partial derivative T)(P) is calculated through the isobaric mode Gruneisen parameter gamma(P) using the lattice parameter data at zero pressure for the phases I and II in NH4I. From the frequency shifts, the specific heat C-P is calculated for the phases studied at zero pressure. Also, the pressure-induced frequency shift, (1/v)(partial derivative v/partial derivative P)(T) is calculated through the isothermal mode Gruneisen parameter gamma(T) at 300 K and it is related to the thermal expansivity alpha(P) for the phases I and II in NH4I.