Structural, elastic, and quasiparticle bandstructure of 4,4 < sup > ′ < /sup > -Bis(nitramino)azofurazan from first principles theory

Abstract

A detailed study on the properties of furazan based energetic material 4,4′-Bis(nitramino)azofurazan (DNAF) using density functional theory (DFT) is presented. Our calculated structural parameters at equilibrium are found to be in good agreement with the experimental results when the van der Waals (vdW) interactions are taken into account. The variation of the lattice parameters with respect to pressure indicates that the crystalline compound is highly compressible along the b-axis, while the calculated bulk modulus is 15 GPa. The variation of the intramolecular bond lengths with pressure shows that the bond between the nitrogen atoms in the nitramine group is more compressible than other bonds. Also, we found the presence of strong hydrogen bonds in the material. The value of elastic constants along different directions is such that C33 > C22 > C11, which can be linked to the impact sensitivity. Knowledge of accurate band gap value, being an important parameter to make a possible correlation with photodecomposition process of energetic materials is very important. As a result the band structure calculations have been carried out using GW approximation along with normal LDA/GGA which are well known to underestimate the band gaps. The calculated band gap from GW approximation found to be 4.9 eV compared to GGA band gap 1.9 eV, indicates the importance of quasiparticle correction in this study.