This study presents an investigation of the effects of adding extra nitro group substituents to N-(3,5-dimethyl-2,4,6-trinitrophenyl)-1H-1,2,4-triazol-3-amine (HEM-II) on its thermal and chemical stability as well as its explosive performance. An analysis of the thermal stabilities of HEM-II and HEM-II-based molecules based on an investigation of the binding energy per atom for each molecule was performed. The values of the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) as well as those of the chemical hardness and softness for HEM-II and the HEM-II-based molecules were studied to determine the chemical stabilities of these molecules. The detonation velocity and oxygen balance of each HEM-II-based molecule were investigated to elucidate its explosive properties. The results of our investigation show that the presence of additional nitro groups suppresses the tendency of the new HEM-II-based explosive material to react with other materials, improves its explosive properties (strength), decreases the likelihood that it will degrade, and enhances its toxicity and thermal stability. We also found that zero-point correction does not need to be performed when molecules with different substituents are investigated and compared.
Keywords: Detonation velocity; Explosive materials; Oxygen balance; Quantum chemistry simulations.