Numerical Sensitivity of Molecular Simulations of Microstructural Interfaces in High Explosives

Many high explosive (HE) formulations are composite materials that contain crystallites of an energetic material that are bound together with a matrix material such as a polymer. Microstructural interfaces between energetic and non-energetic constituents are understood to impact many functional characteristics of HE formulations, including their mechanical strength and their safety and detonation properties. All-atom modeling techniques such as molecular dynamics (MD) can predict the adhesion properties of microstructural interfaces but present several practical difficulties when applied to HEs. General workflows to construct and validate MD simulations of crystal-crystal and crystal-polymer interfaces are presented and used to explore anisotropy in the adhesive properties of organic molecular energetic materials. Mathematical analysis of standard expressions for the surface and interface energy show that these formulas are poorly conditioned. We examine an alternative approach to compute adhesion energy with MD that exhibits better numerical conditioning. Applications of MD simulations to isolate physical and geometric factors governing adhesion and the mechanical properties of microstructural interfaces will be presented along with a prospectus for upscaling these results to coarse grain models.



This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Approved for unlimited release, LLNL-ABS-2002262.