(482i) Ultrafast Detonation of Hydrazoic Acid:Insights from Many-Body Moleculardynamics Force Fields

Understanding the behavior of energetic material under detonation is of interest for a wide range of applications in many fields, such as civil engineering and space exploration. Atomistic molecular dynamics simulations have emerged as a powerful tool to provide valuable insights into such system while circumventing the risks of experimental works. However, due to the short time scales and/or small system size accessible of quantum mechanics simulations and the lack of reliable force fields for molecular mechanics models, very little is known about the chemical evolution and states of matter of an energetic material under detonation. We have developed the Chebyshev Interaction Model for Efficient Simulation (ChIMES), a reactive force field, that retains the accuracy of density functional theory (DFT) simulation while increasing orders of magnitude in computational efficiency. In this work, we use ChIMES to study hydrazoic acid, an azide energetic material that exhibits an ultrafast detonation during a shock wave. We find that our models are able to accurately reproduce the structural properties and chemistry computed from DFT at multiple thermodynamic states. Shock compression simulations using the multiscale shock simulation technique show that our ChIMES models can capture the ultrafast chemical reactions of hydrazoic acid.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.