Microscopic model for propagation of shock-induced detonations in energetic solids

The propagation of shock-induced detonations in solids is studied at the microscopic level by molecular dynamics. The model consists of a two-dimensional lattice of diatomic molecules connected by Morse or Lennard-Jones potentials. A predissociative, exothermic intramolecular potential is used. The model is designed so that a given structure can be imposed on the lattice and parameters are chosen to be consistent with common energetic materials. Detonations propagate in this lattice as coherent waves, and these waves are not destroyed by thermal fluctuations. The role of the coupling between transverse and longitudinal excitations is investigated by varying lattice and potential parameters. The results of the calculations show that there are geometrical conditions on the crystal structure as well as on the intramolecular and intermolecular potentials that must be met to sustain a detonation. Implications for propagation of detonations in energetic materials are discussed.