Qualitatively correlating molecular dynamics simulations and experimental determination of the thermal stability of energetic compounds

Thermal stability is both a fundamental property and an important performance of energetic compounds, and is prone to be understood and predicted by molecular dynamics simulations; still, it is faced up a great challenge in qualitatively correlating the simulations and experimental determinations. This work attempts to address this challenge by correlating ab initio molecular dynamics (AIMD) derived characteristic indexes with DSC and DTG determined onset decomposition temperatures of six energetic compounds, including 1,3,5-triamino-2,4,6-trinitrobenzene, 1,3-diamino-2,4,6-trinitrobenzene; 1,3,5-trinitro-1,3,5-triazinane, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, and pentaerythritol tetranitrate. As results, high correlations (R2) are confirmed therein, i.e., those of the height of potential energy climax and corresponding temperatures, and the temperatures corresponding to low reaction depths (within 0.1 to 0.5) between onset temperatures from DSC test are 0.83, 0.89, and 0.94, respectively; meanwhile, when the proportion of remaining solids reaches 0.98, the correlation between the AIMD simulated temperature and the onset temperature in DTG test is as high as 0.95. Despite a small sample set of six compounds herein, it still exhibits a perspective of first-principles design of energetic materials from molecule to material, instead of molecule only, to remedy the shortcoming of machine learning.