Molecular polarizabilities of some energetic compounds.

The dependence of sensitivity of an explosive on its molecular structure may be mainly attributed to the molecular deformability, which can be expressed by some characteristic parameters, resonance energy for aromatic an explosive, strain energy for a strained-ring or strained-cage explosive, large π-π separation energy for a large π-π linked-explosive, bond rotational energy barriers of C–NO2, N–NO2, O–NO2 for C–NO2, N–NO2, O–NO2 bond-based explosives, and so on. Molecular polarizability of an explosive is also an important molecular deformability index, which can be effectively used to compare impact sensitivities of explosive’s isomers, isoelectronic species, and similar structures. Interestingly, comparing the molecular polarizabilities under external electric fields with different energy levels of isomeric N20(Ih) and N20(D3d) clusters and the Mo2N20 and Re2N20 complex compounds, it is found that there are different energy thresholds of significant molecular expansion.