Groups 3 and 4 share similar elemental compositions as groups 1 and 2 but with broken C-N rings. The decomposition of groups 5, 6, and 7 produces intermediates with a low H/O ratio (see Figure ). Group 8 represents small gas products, including CHNO, H2O, OH, NO, and N2. These species are frequently involved in the reaction network as the product of many reaction pathways. There are two pathways for reactants to release the final gas products: group 1 => 2 => 8; group 1 => 3 and 4 => 5 and 6 => 7 Derived from the overall ICM-102 decomposition (Fig. ), the primary reaction pathways of ICM-102 and the formation of H2O are constructed in Fig. . ICM-102 decomposition starts with intermolecular and intramolecular H transfer to form R-OH species (R1 and R7). These species further decompose into radicals such as OH and H (R2 and R10). The NO2 molecule also abstracts a hydrogen atom from ICM-102 to form HNO2 (R8), which further dissociates as an OH radical (R9). The combination of OH and H radials forms water molecules (R6). The R-OH structures could also undergo ring-opening reactions by C-N bond scission (R3), and this reaction is not preferred due to the high bond energy (305 kJ/mol for C-N bonds ). From the above discussion, the NNMD method breaks through the limitations of AIMD. On the one hand, it extends the timescale of simulation to allow observation of the reaction pathways related to N2, CHNO, CO2 and many other intermediates of ringopening reactions; on the other hand, it expands the system size to thousands of atoms to obtain statistically significant results on the branching of detailed reaction pathways.