An important factor in relation to shock-induced chemistry: resonance energy.

With density function theory BLYP/DNP method, together with homodesmotic reactions and isodesmic reactions, we calculated the resonance energies of some explosives, including eight nitro compounds which contains benzene rings, three nitro compounds which contains azaheterocycles (2,4-dinitroimidazole (2,4-DNI), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) and 2,4,6-trinitro-1,3,5-triazine) and one nitrogen-rich energetic compound of 3,3'-azobis(6-amino-s-tetrazine) (DAAT). The results indicate that their resonance energies are in relation to their shock sensitivity which measuring their threshold pressures of initiation, that is, the lower the resonance energy is, the higher the shock sensitivity of the explosive behaves. And this measuring method according to resonance energy is based on the global property of the molecule instead of the local one, such as one nitro group in the molecule. It is meaningful to calculate resonance energies of these kind of compounds quickly and accurately because resonance structures exist widely in these organic compounds and resonance energies may play a significant role in determining their shock sensitivity, and it is helpful in the rational design or synthesis of high energy and insensitive materials.