Pressure-Mediated Structural Transitions in Nitrogen-Rich 1H-Tetrazole: New Insight from Dispersion Corrected Density Functional Theory Calculations

Heterocyclic nitrogen-rich molecules are widely used as effective precursors for the preparation of high energy density materials, which are denser than their carbon analogs. Here, dispersion corrected density functional theory calculations have been used to study the effect of pressure on nitrogen-rich 1H-tetrazole. A good agreement was achieved between the calculated and experimental crystal structures under ambient conditions. Furthermore, the vibrational spectra were computed by the linear response method as implemented in density functional perturbation theory, and infrared vibrational modes were assigned. The anomaly changes with increasing pressure in the lattice parameters, bond angles, and band structure were observed, indicating that a pressure mediated structural transition occurred around 4 GPa. Subsequently, a mechanism was proposed from the behavior of the vibration spectrum, that is, the structural changes in the 1H-tetrazole molecules were related to the distortion of the ring and CH bond.