Using the force fields due to Nishimura et al.[1] and to Harsanyi et al.[2], dipole moment derivatives (DMD's) and their orientations have been computed byab initiotechniques. The values so computed using the above two force fields are surprisingly close to each other. The DMD's corresponding to the C = O stretching (s) and CN s are found to be among the most significant. The DMD values of C2= O s and C4= O s are found to be comparable in value, both of them thus expected to contribute to C = O s ir band intensities. The DMD's of NH in-plane bending (ipb) modes are found to be surprisingly small, thus explaining the observed absence of splittings due to the corresponding transition dipole- transition dipole coupling (TDC) interactions. The DMD values obtained here are shown to be crucial in deciding which of the observed bands in solid state or condensed phase samples could be due to Fermi resonance and/or overtone and/or combination bands. They could also be used effectively in studying relative ir intensities of samples in condensed phases.