First principles calculations of electronic, vibrational, and thermodynamic properties of 3,6-dinitro-1,2,4,5-tetrazine biguanide

Context and results G(2)(DTNT) as a newly reported nitrogen rich salt energetic material with good stability and detonation performance due to the hydrogen bonding crosslinking between DTNT anions and guanidine cations, demonstrating promising application prospects. This work investigates the electronic structure, vibrational characteristics and thermodynamic properties of G(2)(DTNT) based on first principles. Calculated lattice parameters have good consistency with the values reported in the literature, with an error of no more than 1.42%. The electronic structure of G(2)(DTNT) was studied based on band structure and density of states calculations. Vibration characteristics of G(2)(DTNT) were studied in detail through infrared and Raman spectroscopy, and each peak was assigned to different vibration modes. Phonon scattering curve indicates that G(2)(DTNT) is dynamically stable. In addition, we also calculated the thermal parameters and elastic constants of G(2)(DTNT), and found that it exhibits good thermal and mechanical stability. G(2)(DTNT) has strong deformation resistance along the b and c axes, and the strongest shear strain resistance along the a axis, mainly manifested as toughness. Computational method This study reports a first principles computational method based on DFT for investigating the crystal structure of G(2)(DTNT). Using PBE-GGA and Grimme dispersion correction with DFT-D method to handle exchange related potentials and van der Waals interactions, and OTFG Ultrasoft pseudopotential to describe electron ion interactions. The k-point grid of the Brillouin zone (BZ) is set to 4 x 1 x 1, with a minimum spacing of 0.07 & Aring;(-1), and the force acting on each atom is less than 0.01 eV/& Aring;. Convergence criterion for energy difference is 5.0 x 10(-7) eV/atom, with a cut-off energy of 830 eV. The maximum bulk stress and displacement amplitudes are 0.02 GPa and 5.0 x 10(-4) & Aring;, respectively.