Theoretical prediction on performance of a novel CL-20/bicyclo-HMX energetic cocrystal by MD method

In this article, a novel energetic cocrystal composed of CL-20 and bicyclo-HMX was designed. The crystal models of pure components (CL-20, and bicyclo-HMX) and CL-20/bicyclo-HMX energetic cocrystal models with different molecular ratios were established. Molecular dynamic (MD) method was adopted to optimize the cocrystal structure and predict its properties, including sensitivity, stability, mechanical properties, and energetic performance. Results show that the trigger bond (N-NO 2 bond) energy in CL-20/bicyclo-HMX energetic cocrystal model is increased, meaning that the trigger bond strength is enhanced and the cocrystal explosive should have lower mechanical sensitivity than pure CL-20. The CL-20/bicyclo-HMX cocrystal model with molecular ratio of 2:1 has higher value of binding energy, implying that the intermolecular interaction is stronger and this energetic cocrystal model is more stable. The engineering moduli (bulk modulus, shear modulus, and tensile modulus) of CL-20/bicyclo-HMX energetic cocrystal models are decreased, while Cauchy pressure is increased, indicating that the energetic cocrystal has better mechanical properties than CL-20. The energy density of CL-20/bicyclo-HMX cocrystal explosive is lower than pure CL-20, but much higher than bicyclo-HMX, the energetic cocrystal with molecular ratio of 10:1 ~ 2:1 can be regarded as potential candidate for high energy density compound (HEDC).