Thermal decomposition mechanisms of energetic CL-20-based co-crystals: quantum molecular dynamics simulations

Abstract

The decomposition mechanisms of energetic CL-20 : 2,4-dinitro-2,4-diazapentane (DNP) and CL-20 : 2,4dinitro-2,4-diazaheptane (DNG) co-crystals at high temperatures (1000, 2000 and 3000 K) were studied by density functional tight-binding molecular dynamics (DFTB-MD) simulation. At different temperatures, their decomposition mechanisms are very different. At 1000 K, CL-20:DNG co-crystal undergoes a conformational change from β-CL-20 to γ-CL-20, but CL-20:DNP co-crystal does not occur. When the temperature is increased to 2000 K, CL-20, DNP, and DNG begin to decompose, and there are ve paths for the main initial mechanisms. At 3000 K, the increasing temperature will promote decomposition and the decomposition will be more completely. The initial reaction of CL-20 in two co-crystals has two channels. There are two initial decomposition channels in DNP molecule and only one channel in DNG molecule. With the temperature increases, the decomposition products of two co-crystals are different.Our work contribute to the in-depth understanding of the decomposition mechanisms of high-energy CL-20-based co-crystals at high temperatures.