Theoretical investigation on intermolecular interactions between the ingredients TNT and RDX of composition B

The intermolecular interaction between 2, 4, 6-trinitrotoluene (TNT) and hexahydro-1, 3, 5-trinitro- 1, 3, 5-triazine (RDX), which were the main components of Composition B, were studied at B3LYP/6-31G (d) level. The optimized conformations of the ten forms were obtained. The geometrical parameters, stability, electronic structures and harmonic vibrational frequencies were investigated for the optimized structure at the same level. Natural bond orbital (NBO) analyses were performed to reveal the origin of intermolecular interaction between TNT and RDX. The hydrogen bonds contribute to the interaction energies dominantly. The intermolecular interactions are within a range of -3.930~-14.652 kJ • mol^-1, and the binding energy corrected for the basis set superposition error (BSSE) is in the order of VI > III >V >IV >X >I >IX >II > VII > VIII. The changes of thermodynamic properties from monomer to complexes were discussed. It can be found that the formation of hydrogen bonds is exothermic process. Finally, the detonation performances were estimated by using the Kamlet-Jacobs equation. The reliability of this theoretical method and results were tested by comparing the theoretical values of ρ, p and D with experimental or referenced values.