Figure 1

(Color) Two views of the molecular structure of HMX. Gray, carbon; blue, nitrogen; red, oxygen; and white, hydrogen. The geometry shown corresponds to the $\alpha$ polymorph.Reuse & Permissions

Figure 2

(Color) Shock Hugoniot locus in the $\left(u_s\text{−}{u}_p\right)$ plane for $\alpha \text{−}\mathrm{HMX}$ shocked in the [100] direction. Upper inset: $\alpha \text{−}\mathrm{HMX}$ crystal structure. Lower inset: representative position versus time plots for elastic and plastic waves for $u_p=0.75\mathrm{km}∕\mathrm{s}$, from which the corresponding velocities were obtained.Reuse & Permissions

Figure 3

(Color) Snapshots of intermolecular and intramolecular temperatures (red and black, respectively) plotted versus distance along the shock direction. The snapshots were taken close to points of maximum compression, for shocks propagating from left to right: (a) shock strength below the Hugoniot elastic limit, (b) shock strength within the elastic-plastic region, and (c) overdriven shock.Reuse & Permissions

Figure 4

(Color) Depictions of plasticity in HMX for shock states spanning the two-wave region. Results are for individual snapshots taken near maximum compressions. (a)–(c) Distributions of local molecular displacements, ${\Delta }_{ij}\left(t\right)$, projected onto the (010) plane. (d)–(f) Dislocations and shear bands at the “surface” of the simulation cell. Red and green correspond to $b=1∕2\left[101\right]$ and $1∕2\left[10\overline{1}\right]$ dislocations, respectively; blue corresponds to shear bandlike deformation. (g)–(i) As in (d)–(f) except that the view is through the simulation cell in a direction normal to the (010) plane. (j) Radial distribution functions for elastically compressed molecules (black) and those that have undergone dislocation slip (red) or nanoscale shear-band deformation (blue). The shock strength is $u_p=0.75\mathrm{km}∕\mathrm{s}$.Reuse & Permissions

Figure 5

(Color) (a) and (b) Spatial distributions of intermolecular temperature in $\alpha \text{−}\mathrm{HMX}$ for two shock strengths in the elastic-plastic region. (c) and (d) As in (a) and (b) except that the plots depict those molecules that have undergone conformational change. (e) Percentage versus shock strength (piston velocity) of molecules that remain in the $\alpha$ conformation at the end of the simulations. Black, red, and blue correspond to molecules in regions of elastic compression, dislocation slip, and shear bandlike local plastic deformation, respectively.Reuse & Permissions