The role of electric field on decomposition of CL‐20/HMX cocrystal: A reactive molecular dynamics study

Abstract

Electric field can initiate decomposition or detonation of explosives, but underlying mechanism is unclear. Here, we performed ReaxFF molecular dynamics simulation for

Roles of Small Molecules in the Stability and Sensitivity of CL-20-Based Host–Guest Explosives under Electric Fields: A Reactive Molecular Dynamics Study

“…Such ST tendency agrees with the experimentally observed phase transition of ε-CL-20 induced by pressure 14 or heat 13 and is also consistent with the reported trend of CL-20 under the EF. 29 27 Hence, we focused on the C−N 5 bond rupture of the first 15 decomposed CL-20 molecules without reacting with small guest molecules. By analyzing trajectory files of simulations using our FORTRAN code, we determined whether and how the CL-20 molecules would undergo ST and collected the results in Table S3.…”

“…This effect of N 2 O in decreasing the sensitivity of CL-20 is similar to the effect of HMX in the CL-20/HMX cocrystal. 3,27 To further understand the effect of H 2 O 2 and N 2 O on decomposition of CL-20, we divide the reactions during the decomposition into two categories, that is, host molecules' reactions and guest molecules' reactions. The statistical threshold is that the frequency difference between forward and reverse reactions is greater than 10 and 5 for host and guest molecules' reactions, respectively, as shown in Table 3, in accordance with the thermal decomposition case of α-CL-20/ H 2 O 2 .…”

“…34 Accuracy of ReaxFF-lg has been verified in detail in case of thermal decomposition of CL-20/H 2 O 2 21 and our previous study of EF-induced decomposition of CL-20/HMX. 27 The unit-cells of four EMs ε-CL-20, α-CL-…”

“…To understand the anisotropic crystal structure of the explosives, we defined a physical quantity M to characterize the distribution of C−N bonds in five-membered rings (FMRs) of CL-20 (shorthand for C−N 5 in the following parts), which is the most easily stretched bond in the CL-20 molecule under the EF. 27 M was calculated for relaxed supercells of the four explosives as follows.…”

“…Some theoretical studies have devoted to elucidating the role of small molecules in increasing the energy performance of CL-20. ,, However, a theoretical study in the sensitivity of CL-20-based host–guest explosives is yet scarce and the underlying mechanism that small molecules affect sensitivity is still unclear. Moreover, electrostatic catalysis, that is, chemical reactions affected by an external electric field (EF), attracts the attention of many researchers, , and it was also found that the EF has great impact on decomposition and detonation of EMs. − Furthermore, electric spark, which may exist in the whole life circle of EMs and is vital to the safety of explosives, is usually accompanied by a strong EF. Recent COMPASS MD simulations , found that CL-20 molecules would undergo structural transformation (ST) under an external EF.…”