Jp. Lewis et al., Ab initio calculations of reactive pathways for alpha-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (alpha-HMX), J PHYS CH A, 104(48), 2000, pp. 11384-11389
Using the BLYP and B3LYP level of density functional theory, four possible
decomposition reaction pathways of HMX in the gas phase were investigated:
N-NO2 bond dissociation, HONO elimination, C-N bond scission of the ring, a
nd the concerted ring fission. The energetics of each of these four mechani
sms are reported. Dissociation of the N-NO2 bond is putatively the initial
mechanism of nitramine decomposition in the gas phase. Our results find the
dissociation energy of this mechanism to be 41.8 kcal/mol at the BLYP leve
l and 40.5 kcal/mol at the B3LYP level, which is comparable to experimental
results. Three other mechanisms are calculated and found at the BLYP level
to be energetically competitive to the nitrogen-nitrogen bond dissociation
; however, at the B3LYP level these three other mechanisms are energeticall
y less favorable. It is proposed that the HONO elimination and C-N bond sci
ssion reaction of the ring would be favorable in the condensed phase.