Simulations of the structure, vibrational spectra, and energy content of crystalline bis (4-amino-3,5-dinitropyrazolyl) methane under high pressures.

The crystalline structure of bis (4-amino-3,5-dinitropyrazolyl) methane (BDNAPM) was optimized from ambient pressure to 40 GPa using density functional calculations in order to understand pressure-induced instabilities. Raman spectra were calculated as a function of pressure using density functional perturbation theory and linear response for lattice dynamics. The zone center (k$=$0) optical modes provided information about the vibrational modes of the crystal. The calculated spectra were compared with high-pressure experimental spectroscopic measurements in the same pressure range. The enthalpy of formation was calculated along with the mass density for simulation of Chapman-Jouguet characteristics.