Theoretical study of potential energetic material PETN/DNTF eutectic explosive based on molecular dynamics method

Research on novel co-crystals has long been a focal point in the field of high-energy material modification. In the present exploration, density functional theory (DFT) and molecular dynamics (MD) simulations were employed to investigate the properties of pentaerythritol tetranitrate (PETN)/3,4-dinitrofurazanofurazan (DNTF) mixtures across a molar fraction interval of 9:1 to 1:9. This study incorporated a comprehensive analysis of multiple key characteristics, encompassing the surface electrostatic potential of molecules, atomic interaction lines, binding energy values, trigger bond lengths, cohesive energy density, together with the mechanical behaviors of the designated assembly. Additionally, the detonation characteristics of pure PETN, pure DNTF, and the PETN/DNTF system were predicted using the EXPLO-5 software in conjunction with the nitrogen equivalent coefficient (NEC) method.

The outcomes of the study uncovered significant divergences in the surface electrostatic potential of PETN versus DNTF molecules. These disparities indicate that intermolecular interactions across different molecular species are stronger than the interactions within homogeneous molecular groups, which in turn points to the viability of co-crystal synthesis between PETN and DNTF. A peak value of binding energy was ascertained at a molar ratio of 3:7, indicating the highest likelihood of co-crystal formation at this composition. The primary driving forces for co-crystallization were identified as electrostatic forces and van der Waals forces. The as-obtained co-crystal explosive demonstrated modest sensitivity and intermediate mechanical behavior. In a similar vein, the detonation behavior of the co-crystal at a molar ratio of 3:7 fell between that of pure PETN and pure DNTF, positioning it as a novel type of insensitive high-energy material.

Materials Studio software was utilized to forecast the characteristics of PETN/DNTF co-crystals with varying molar ratios and crystal planes via molecular dynamics (MD) simulations. The MD simulations were performed with a time step of 1 femtosecond (fs) and a total simulation duration of 2 ns (ns). An isothermal-isobaric (NPT) ensemble was employed for the 2 ns MD simulations. The COMPASS force field was adopted, with the temperature set at 295 Kelvin (K). For the prediction of detonation characteristics, the EXPLO-5 software was combined with the nitrogen equivalent coefficient (NEC) method.