Periodic DFT Study on High Pressure Behavior of Nitrogen-rich Energetic Crystal 4-Amino-3, 7-Dinitrotriazolo-[5, 1, c][1, 2, 4] Triazine

Abstract

The high pressure behavior of nitrogen-rich energetic crystal 4-amino-3, 7-dinitrotriazolo-[5, 1, c] [1, 2, 4]triazine (DPX-26) in the hydrostatic pressure range of 0-130 GPa was investigated by employing the GGA/PBE-G06 method of periodic density functional theory (DFT). The changes of crystal structure, molecular structure and electronic structure of DPX-26 with pressure were analyzed by calculating lattice parameters (a, b, c), bond lengths, band gaps (ΔEg) and density of states (DOS). The results show that DPX-26 undergoes three significant structure transitions at 81, 82 and 92 GPa. The structural transformation occurs at 81 GPa with the destruction of intermolecular six membered rings. At 82 GPa, the triazole ring is severely distorted and dissociated with the elongation of C4-N7 bond. As the pressure reaches 92 GPa, the bond length of C4-N7 decreases from 0.2324 nm to 0.1333 nm, and the triazole ring is formed again. The increase of external pressure leads to the delocalization enhencement of the system.