Using the BLYP and B3LYP level of density functional theory, four possible decomposition reaction pathways of HMX in the gas phase were investigated: N-NO 2 bond dissociation, HONO elimination, C-N bond scission of the ring, and the concerted ring fission. The energetics of each of these four mechanisms are reported. Dissociation of the N-NO 2 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 level 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 nitrogennitrogen bond dissociation; however, at the B3LYP level these three other mechanisms are energetically less favorable. It is proposed that the HONO elimination and C-N bond scission reaction of the ring would be favorable in the condensed phase.

The results of a first principles simulation of the Cu(110)–water interface are presented. The calculations were carried out using ab initio Car–Parrinello molecular dynamics simulation within a pseudopotential formalism and the BLYP generalized gradient approximation to the exchange-correlation potential. An analysis of the structural properties of the interface shows that absorption of H2O molecules occurs on the metal top sites which is in agreement with experimental results. The electronic structure of the interface has also been explored. It was found that there is a strong coupling of the water overlayer with the metal crystal electronic states. However, the surface-states charge density is undisturbed by the presence of water. The empty surface states are seen to not be quenched by the presence of water, which is also in qualitative agreement with existing experiments.