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Early Decay Mechanism of Shocked ε‑CL-20: A Molecular Dynamics Simulation Study
journal contribution
posted on 2016-09-02, 00:00 authored by Xianggui Xue, Yushi Wen, Chaoyang Zhangε-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane
(CL-20) is currently the most powerful explosive commercially available.
Nevertheless, the early decay events of shocked ε-CL-20 still
remain unclear. We perform quantum based self-consistent charge density-functional
tight-binding molecular dynamics simulations, in combination with
the multiscale shock simulation technique, to reveal the events with
four specified shock velocities (Us) of 8 to 11 km/s. We find that
the temperature and pressure increases and that the volume reduction
is enhanced with increasing shock strength. The ring opening is observed
to trigger molecular decay at all four shock conditions; while the
sufficient NO2 fission is observed at Us = 8 and 9 km/s,
and strongly inhibited at Us = 10 and 11 km/s. Moreover, the evolution
of main chemical species, such as active intermediates, stable products,
and clusters, is strongly dependent on the shock strength. NO2 and H are dominant in the primary intermediates, responsible
for weak and strong shock, respectively; CO2 and N2, as well as water, are the main stable products with a population
gradation determined by the shock strength; and the bigger clusters
with longer durations are found to be caused by the stronger shock,
and their fast dissociation mainly undergoes through the ring opening.
Besides, it is found that ε-CL-20 possesses weak anisotropy
in the above-specified Us range. This work will enrich the knowledge
of shocked energetic materials, in particular, the important energetic
materials.