First-principles investigation of the structural stability of TKX-50 under high pressure

Dihydroxylammonium 5,5 '-bistetrazole-1,1 '-diolate (TKX-50) is a kind of energetic material with high energy, low sensitivity, environmental friendliness, and low toxicity. To understand the structural stability of TKX-50 under high pressure, the lattice parameters, band gaps, intermolecular bond length and bond angle, phonon spectrum and Raman spectra of TKX-50 with pressure were calculated based on the GGA-PBE + G functional by using the first-principles density-functional theory (DFT). There is a good stability of TKX-50 in lattice dynamics under a wide range of static pressures (0-165 GPa). TKX-50 shows strong anisotropy in compressibility and stability. c-axis is the most stable in compressibility and structural stability than a and b-axis. At 149 GPa, a fracture of the intramolecular hydrogen-bond O2-H1MIDLINE HORIZONTAL ELLIPSISO1 occurred, which should lead to the structure phase transition.