Abstract: The main requirements of energetic materials are high performance, insensitiveness, eco-friendly nature so that these materials can find tremendous applications in both civil and military sectors. Ammonium DiNitramide (ADN) is one of the most promising green energetic oxidizers for future rocket propellant formulations. In the present talk, I will discuss the structural, mechanical, and spectroscopic properties of AND and Ammonium Perchlorate from first-principles theory. Strength of intermolecular interactions has been correlated using the calculated compressibility curves and elastic moduli. Discontinuities in the structural parameters and elastic constants are observed as a function of pressure. In addition, the computed infra-red (IR) spectra at ambient pressure reveal that ADN is found to have more hygroscopic nature over Ammonium Perchlorate (AP) due to the presence of strong hydrogen bonding. Pressure dependent IR spectra show blue- and red-shift of bending and stretching frequencies which leads to weakening and strengthening of the hydrogen bonding below and above 5 GPa, respectively. The abrupt changes in the calculated structural, mechanical, and IR spectra suggest that ADN might undergo a first order structural transformation to a high pressure phase around 5-6 GPa.