Molecular dynamics (MD) study to predict performances of a novel hexanitrohexaazaisowurtzitane/1,4-dinitroimidazole (CL-20/1,4-DNI) energetic cocrystal under different temperatures.

Context: To estimate the influence of temperature on properties of 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane/1,4-dinitroimidazole (CL-20/1,4-DNI) cocrystal explosive, the supercell crystal of CL-20/1,4-DNI cocrystal model was established. The mechanical properties, sensitivity, and stability of cocrystal model under different temperatures (T = 225 K, 250 K, 275 K, 300 K, 325 K, 350 K) were predicted. Results show that mechanical parameters, including bulk modulus, tensile modulus and shear modulus are the lowest when temperature is 300 K, while Cauchy pressure is the highest, indicating that CL-20/1,4-DNI cocrystal model has better mechanical properties at 300 K. Cohesive energy density (CED) and its components energies decrease monotonically with the increase of temperature, illustrating that the CL-20 and 1,4-DNI molecules are activated and the safety of cocrystal explosive is worsened with the increase of temperature. Cocrystal model has relatively higher binding energy when the temperature is 300 K, implying that the CL-20/1,4-DNI cocrystal explosive is more stable under this condition.

Methods: The CL-20/1,4-DNI cocrystal model was optimized and the properties were predicted through molecular dynamics (MD) method. The MD simulation was performed with COMPASS force field and the ensemble was set as NPT, external pressure was set as 0.0001 GPa.