CPMD investigation of α-RDX and ϵ-CL-20: The transition of deflagration to detonation depending on the self-produced radicals

1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are the classic high energy nitramine compounds. Herein, we performed simulations of the overall decomposition pathways of condensed α-RDX and ϵ-CL-20 by applying the Car-Parrinello molecular dynamics (CPMD) method. Both of them appear to have similar distinct initial decomposition pathways, which are the bond cleavages of N-NO₂ bonds. Interestingly, we find that the continuous explosion is nonspontaneous without the participation of self-produced hydrogen radicals of RDX or oxygen radicals of CL-20. Increased radicals are produced gradually with increasing temperature, which activates further entropy-increased steps, resulting in the uncontrollable transition of deflagration to detonation with the formation of NO_x, CO_x and HCN.