FURTHER-STUDIES OF THE CLASSICAL DYNAMICS OF THE UNIMOLECULAR DISSOCIATION OF RDX

Classical trajectories have been used to compute the unimolecular dissociation rates of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) for total energies over the range 200-450 kcal/mol. The purpose of the study was to further refine the potential-energy surface. Thus, calculations were carried out on various surfaces, and results are reported for three of them. The three surfaces are similar except for the barrier height for the triple bond-fission reaction which gives 3CH(2)NNO(2) as products; rates are reported for barriers of 37, 56, and 71 kcal/mol for this channel. The energy required for the other primary dissociation channel, simple N-N bond fission, is about 48 kcal/mol far the three surfaces. The two surfaces with the higher barriers to ring fission yield branching ratios (ring fission to bond rupture) that appear to be inconsistent with the value determined from the infrared multiphoton dissociation experiments of Zhao et al. (J. Chem. Phys. 1988, 88, 801).