  The shock to detonation transition in heterogeneous plastically bonded
explosives is dominated by energy localization into hotspots that arise from
the interaction of the shockwave with microstructural features and defects. The
complex polycrystalline structure of these materials leads to a network of
hotspot that can coalesce into deflagration and detonation waves. Significant
progress has been made on the formation and potency of hotspots using atomistic
simulations, but most of the work has focused on ideal and isolated defects.
Hence, developed a method, denoted PBXGen, to build realistic PBX
microstructures for all-atom simulations. PBXGen is generally applicable, and
we demonstrate it with two systems: an RDX-polystyrene PBX with a 3D
microstructure and a TATB-polystyrene with columnar grains. The resulting
structure exhibit key features of PBXs, albeit at smaller scales, and are
validated against experimental mechanical and shock properties.
