Thermal Stability Difference between NQ and NOG: Insights from Pyrolysis Reactions via First-Principles Molecular Dynamic and Quantum Chemistry Modeling.

The thermal stability differences between NQ and NOG were investigated by examining their initial decomposition mechanisms at both the molecular and crystalline scales using density functional theory calculations. First-principles molecular dynamics simulations revealed that NQ primarily undergoes intermolecular hydrogen or oxygen atom transfer reactions, while NOG preferentially decomposes through a ring-opening reaction. Analysis of decomposition product evolution demonstrated that NQ decomposes faster at high temperatures, with the decomposition products of both compounds being strongly dependent on their molecular structures. Quantum chemistry calculations showed that NOG molecules exhibit higher energy barriers for the same unimolecular decomposition pathways compared to NQ. Furthermore, two reversible reactions, hydrogen transfer and bond rotation, were identified as key factors enhancing NOG's thermal stability. These findings significantly advance our understanding of structure-property relationships in energetic materials while providing valuable insights into studying energy release mechanisms and designing novel energetic compounds.