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.

Theoretical Prediction on Properties of 3,4-Bisnitrofurazanfuroxan (DNTF) Crystal and its Polymer Bonded Explosives (PBXs) Through Molecular Dynamics (MD) Simulation.

CONTEXT: 3,4-Bisnitrofurazanfuroxan (DNTF) is a typical high energy density compound (HEDC), it has high crystal density and detonation parameters, but also high mechanical sensitivity. To decrease its mechanical sensitivity, the DNTF based polymer bonded explosives (PBXs) was designed. The pure DNTF crystal and PBXs models were established. The stability, sensitivity, detonation performance and mechanical properties of DNTF crystal and PBXs models were predicted. Results show that PBXs models containing fluorine rubber (F2311) and fluorine resin (F2314) have higher binding energy, meaning that DNTF/F2311 and DNTF/F2314 is relatively more stable. PBXs models have higher value of cohesive energy density (CED) than pure DNTF crystal, DNTF/F2311 and DNTF/F2314 have the highest value of CED, implying that the sensitivity of PBXs is effectively decreased, DNTF/F2311 and DNTF/F2314 is more insensitive. PBXs have lower crystal density and detonation parameters than DNTF, the energy density is declined, DNTF/F2314 has higher energetic performance than other PBXs. Compared with pure DNTF crystal, engineering moduli (tensile modulus, shear modulus, bulk modulus) of PBXs models are obviously decreased, but Cauchy pressure is increased, implying that the mechanical properties of PBXs is superior to pure DNTF component, the PBXs containing F2311 or F2314 have more preferable mechanical properties. Consequently, DNTF/F2311 and DNTF/F2314 have the best comprehensive properties and is more attractive among the designed PBXs, indicating that F2311 and F2314 are more advantageous and promising in ameliorating properties of DNTF. METHODS: The properties of DNTF crystal and PBXs models were predicted through molecular dynamics (MD) method under Materials Studio 7.0 package. The MD simulation was performed with isothermal-constant volume (NVT) ensemble, and the force field was chosen as COMPASS force field. The temperature was set as 295 K, the time step was 1 fs and the total MD simulation time was 2 ns.