First Principles Investigation of Nitrogen-Rich Energetic Materials

The polymorphism of the highly energetic crystal TKX-50 is investigated as a function of hydrostatic pressure using first-principles evolutionary crystal structure prediction methods. Crystal structures are built using the bistetrazole-diolate (C2N8O2) and ammonium hydroxyl (NH3HO) molecular motifs. The pressure-induced polymorphic phase transitions from the ambient pressure phase to phases with C2/c and P2(1)/c space groups are predicted to occur at pressures of 19.9 GPa and 30.2 GPa respectively. The crystal structures of these two phases have different hydrogen bond lengths, which may affect the sensitivity of this energetic material.