Ab Initio Molecular Dynamics on Energetic Materials and Detonation Mechanisms

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Authors
  1. Zhang, F.
  2. Woo, T.K.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN);University of Western Ontario, London ONT (CAN) Dept of Chemistry
Abstract
The development of ab initio or “first principles” molecular dynamics, along with the rapid development of computer power, has inspired us to apply it to studies of energetic materials and detonation processes. Using Car-Parrinello ab initio molecular dynamics, a multimolecular collision model and a controlled temperature bulk liquid compression approach have been developed to study atomic-level decomposition mechanisms of homogeneous liquid energetic materials under shock and highly static compressed conditions. Liquid nitromethane was chosen as a prototypical molecular explosive. In multimolecular collision simulations, neighbouring molecules act as traps to confine the recoiling fragments produced during the initial collision, thereby allowing them to recombine. This results in higher threshold collision velocities than previously found with binary collision simulations. These threshold velocities (8-10 km/s) are higher than average atomic velocities expected at the detonation shock from, suggesting that molecular dissociation may occur with thermalization after the shock front passes. These threshold velocities also suggest that the excitation of kinetic motion degrees of freedom within the shock front can be a mechanism only for detonation initiation of a new generation of molecular explosives whose detonation velocities would be several times that of current molecular explosives. In bulk liquid compression simulations at controlled temperature (150-300 K), the activ

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Report Number
DRDC-SUFFIELD-TR-2003-156 — Technical Report
Date of publication
01 Dec 2003
Number of Pages
45
DSTKIM No
CA024357
CANDIS No
521928
Format(s):
CD ROM

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