Molecular dynamics study of heating rate effects on 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) decomposition

XF Wei and S Sha and QY Duan, THEORETICAL CHEMISTRY ACCOUNTS, 144, 87 (2025).

DOI: 10.1007/s00214-025-03237-x

This study aimed to investigate the thermal decomposition of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105, C4H4N6O5) under heating rates of 20, 40, 60, and 80 K/ps using molecular dynamics simulations. The thermal decomposition simulations with all systems- controlled heating spanning from 300 to 3000 K. Results revealed that at 300-3000 K, an inverse correlation exists between heating rate and decomposition rate, while the initial decomposition temperature exhibits positive dependence on heating rate, both trends aligning with experimental data. The thermal decomposition mechanism of LLM-105 exhibits insensitivity to heating rate variations. The quantum chemical calculations and molecular dynamics simulations consistently identify -NO2 group detachment as the initial step in LLM-105 thermal decomposition. -HO forms during the latter half of the decomposition process, corresponding to the second step, while the cleavage of the benzene ring structure takes place in the final stage. At 300-3000 K, the heating rate remarkably influences the formation quantity of thermal decomposition products in LLM-105, particularly late-stage decomposition products. Lower heating rates prolong the decomposition process, allowing extended collision reaction durations and higher recombination probabilities, thereby increasing the yields of stable products such as H2O, CO2, and N2. However, higher heating rates reduce these quantities because of shortened reaction times.

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