Pressure-induce structural changes of 1,1-diamino-2-nitro-2-(1-amino-1H--tetrazol-5-yl) ethene: An insensitive FOX-7-like energetic materials

We have conducted ab initio calculations using density functional theory to investigate the structural, vibrational, and mechanical properties of 1,1-diamino-2-nitro-2-(1-amino-1H-tetrazol-5-yl) ethene, as a promising high-performance explosive. The effect of high pressures, up to 50 GPa, on the structure shows that there exists a possible pressure-induced structural transition around 21 GPa. The pressure-dependent intermolecular close contacts support the notion that molecular geometry is deformed and then rearranged to achieve a new equilibrium. Furthermore, we interpret significant molecular and intermolecular changes with assistance from calculated vibrational spectrum analysis. Apart from this, the calculated elastic constants demonstrate mechanical instability above 20 GPa, which aligns with the aforementioned structural change. Finally, we report bulk moduli, Young's moduli, shear moduli, and Poisson's ratio (nu), and the brittleness/ductility characteristics under high pressure are also analyzed.