Intermolecular Interactions, Thermodynamic Properties, Detonation Performance, and Sensitivity of TNT/CL-20 Cocrystal Explosive

Intermolecular interactions and properties of TNT (2,4,6-trinitrotoluene)/CL-20 (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane) cocrystal were studied by density functional theory (DFT) methods. Binding energy, natural bond orbital (NBO), and atom in molecules (AIM) analysis were performed to investigate the intermolecular interactions in the cocrystal. Results show that the unconventional CH center dot center dot center dot O type hydrogen bond plays a key role in forming the cocrystal. The variation tendency of entropy and enthalpy shows that the formation of the cocrystal is an exothermic process and low temperature will be benefit for the assembling of complexes. The calculated detonation velocity of the cocrystal agrees well with the experimental value which is higher than that of the physical mixture of TNT and CL-20. In addition, bond dissociation energies (BDEs) of the weakest trigger bond in TNT/CL-20 complex were calculated and the results show that the TNT/CL-20 complex is thermally stable. Finally, first-principles calculations were performed and analysis of the nitro group Mulliken charge indicates that the cocrystal is less sensitive than pure CL-20.