Molecular Design of New Energetic Materials: Calculation of Performances and Thermal Stability

摘要

New energetic materials must combine high performance with low vulnerability. We apply a predictive approach at the molecular level to identify the best candidate compounds satisfying required specifications. Performances depend on density and formation enthalpy. To predict density, we apply a group contribution method. Solid-state formation enthalpies, △_fH°(sol), are obtained from the difference between gas phase values, △_fH°(gas), and sublimation enthalpies, △_(sub)H°. To estimate △_fH°(gas), we apply either the PIMM force field or Density Functional Theory techniques (DFT), depending on the required accuracy. To estimate △_(sub)H°, we use an explicit expression to represent the involved molecular factors. The discrepancy between observed and calculated values of △_fH°(sol) meets the accuracy required for thermochemical calculations. Vulnerability includes thermal stability. Prediction of this property is a complex problem and in a preliminary attempt, we correlated experimental decomposition temperature with a dissociation energy calculated in the PM3 semi-empirical approach.