Nitromethane potential energy surface

The complete potential energy surface of nitromethane, ad-nitromethane and methyl nitrite is accurately known by experiment (Figure 7)52. Thus, the ad-nitromethane radical cation, based on appearence energy measurements, has been found as the more stable by 6 kcal mol-1. ... 

FIGURE 7. The potential energy surface of nitromethane, aci-nitromethane and methyl nitrite52. The dots indicate transitions determined from daughter ion appearance energies52. Such values may possess a significant kinetic shift3... 

Although the mechanism is far from completely determined (which is not surprising given its complexity), there are sufficient details to invite attempts to simulate the chemistry of this prototypical energetic material. Its size permits accurate ab initio calculations to determine the potential energy surface of the reactions in the proposed mechanism many of the secondary reactions are of interest in other combustion systems and have been studied by various experimental and theoretical approaches. Even a cursory discussion of the theoretical studies of secondary reactions involved in the decomposition of nitromethane is beyond the scope of this chapter we limit the discussion to the initial decomposition steps. 

In their study of the decomposition of nitromethane, Rice and Thompson [94] introduced a new approach for constructing potential energy surfaces for many-atoms systems that react via multiple pathways. The basic idea of the approach is to construct potentials that accurately describe the various equilibrium regions, e.g., reactants and products, and then write the overall global potential as Vtotal=E SjV where j denotes the various stable species, the Vi are the analytical potentials for those species, and the Sj are weighting functions that effect a switching between the potentials... 

ABSTRACT Work has begun at RARDE to attempt to elucidate the complex chemistry of reacting explosives using molecular orbital calculations to describe possible potential energy surfaces for decomposition. The well-known sensitising effect of amines on nitromethane is modelled by studies of the nitromethane/ammonia system. The calculations lead to a new proposal for a mechanism for decomposition. This mechanism is supported by experimental data. 

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