Decomposition of DADNE and NQ

The course of dynamic trajectory for DADNE and NQ is very different from that for RDX and P-HMX, as one can see from the comparison of Fig. 3 -7. The difference is in the time dependence of kinetic energy after the start of decomposition process. In case of RDX and P-HMX the kinetic energy starts to increase dramatically during the decomposition, anyway the increase is monotonous. Decomposition of DADNE and NQ starts with the rupture of N-H bond followed by the rupture of C-N bond. However in this case the decomposition is accompanied with the large fluctuations of kinetic energy, as one can see in the Fig. 6 and 7. 

Analysis of dynamic trajectories enabled us to determine two parameters, characterizing the decomposition process  

To compare the reaction pathways R1 and R2 we analyzed dynamic trajectories for RDX corresponding to the process R1 and R2 in the Fig. 3 and 4. The parameters estimated from these two trajectories are  

These parameters are summarized in the Table 2. As one can see in Table 2, the release of the first nitro-group and the gradual rupture of C-N bonds may differ in various reaction pathways Rl, R2 or in mixed Rl/2 pathway. It is evident, that the instantaneous value of Ek(NOz) obtained from one dynamic trajectory only, can not be the reliable characteristics of decomposition process. On the other hand the parameters Ek (d) and AEm do not change significantly for various trajectories corresponding the same molecule and can serve as characteristics of decomposition process for a given molecule. 

The comparison of calculated and experimental characteristics for all investigated molecules is in the Table 1. As one can see the Ek(N02) parameters exhibit the same trend as the h values in dependence on the molecule type. On the other hand, the course of AE o values agrees with the course of the detonation energy ED in dependence on the molecule type. Both calculated parameters Ek(N02) and AEm obtained from the classical molecular dynamics simulations agree with the experimental characteristic h and calculated values of ED in Ref. 5,16. 

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