An effect of charged and excited states on the decomposition of FOX-7

Various decomposition mechanisms in 1,1-diamino-2,2-dinitroethylene (FOX-7) in both gas and solid phases have been investigated by means of density functional theory calculations using an embedded cluster model. We found that the molecular excitations and charge trapping have a dramatic effect on the decomposition process by facilitating some mechanisms of dissociation and precluding the others; the excited states not only reduce the energetic reaction barriers but also change the type of the dominating chemistry from endothermic to exothermic. We found that the decomposition of FOX-7 in the gas phase is defined by two competing low- energy mechanisms, the C-NO$_{2}$ scission and C-NO$_{2}$ to CONO isomerisation. Decomposition in solid state of FOX-7 is much more complex and is controlled by cooperative behavior, which involves the excitation processes and structural inhomogeneities in crystalline lattice.