Molecular packing-dependent thermal decomposition pathways in 3,4-dinitrofurazanfuroxan: insights from SCC-DFTB molecular dynamics simulations.

This work investigates the influence of molecular packing arrangements on the initial thermal decomposition mechanisms of 3,4-dinitrofurazanfuroxan (DNTF) using self-consistent charge density functional tight-binding (SCC-DFTB) molecular dynamics simulations. Ordered and disordered DNTF models were constructed and subjected to programmed heating (300-3000 K) and constant temperature heating conditions (2000 K, 2500 K and 3000 K). The ordered model exhibited diverse decomposition pathways, including nitro group dissociation (R5) and multiple N-O bond cleavages (R1-R4), while the disordered model predominantly followed the low-energy-barrier R1 pathway (central ring N-O cleavage). Potential energy analysis revealed higher energy peaks and faster decomposition kinetics in the ordered configuration. Fragment evolution profiles demonstrated distinct decomposition mechanisms: the disordered model favored furoxan ring-opening, whereas the ordered model preferentially decomposed nitrofurazan rings. Additionally, the disordered model exhibited earlier decomposition onset but slower kinetics compared to the ordered system. These findings highlight the critical role of molecular packing in modulating thermal stability and decomposition pathways, providing insights for optimizing the safety and performance of melt-cast explosives.