produced from the homolytic fission of the N-NO2 bond in RDX molecules. This finding is consistent with previous works as the breakage of N-NO2 bond triggers the RDX decomposition. Chakraborty et al. identified the first bond-breaking event as N-NO2 bonds in a single RDX molecule compared to the HONO elimination and concerted ring break. The corresponding dissociation energy is the lowest among the other two potential reactions computed by the B3LYP method. The NO2 molecules are subsequently consumed in a rapid manner within 10 ps, followed by the production of NO and H2O molecules. In the later stage, the production of N2 and CO2 are observed, and the overall reactions reach an equilibrium after 100 ps. The production of NO2, NO, HNO2, H2O, and CO2 is also reported in a recent FTIR experiment .The RDX decomposes into NO2, NO and H2O first, and then NO2 and NO starts to decrease after a certain time, while H2O continues to increase. Although the experiments are performed at a lower temperature (e.g. 538K), the product evolution agrees with our NNP simulations qualitatively. The predicted species evolution using the ReaxFF model is included in Figure . The overall evolution is similar with the NNP results, where NO2 is the major intermediate, and N2, H2O, and CO2 are the major products. Compared with the results of ReaxFF model, the NNP predicts more NO molecules, a faster H2O production rate, and a higher N2 concentration at the equilibrium. To validate the accuracy of the NNP in species evolution, the evolution of NO2, NO, and H2O are also compared in Fig. , indicating that the NNP outperforms the ReaxFF model in the prediction of the decomposition process. In addition, the NNP predicts that N2 is the most abundant final product, followed by H2O and CO2. This finding agrees with the experiments where the final products of RDX decomposition is 37% N2, 31% H2O, 18% CO2, and 14% CO. It should be noted that the NNP predicts a lower concentration of CO, because PBE method underestimates the stability of CO . The current NNP inherits this issue to some extent, and further improvement can be carried on to add more accurate DFT calculations of CO-involved reactions in the training set.