Generalized stacking fault energies in the basal plane of triclinic molecular crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
N Mathew and TD Sewell, PHILOSOPHICAL MAGAZINE, 95, 424-440 (2015).
Molecular dynamics and molecular statics simulations were used to investigate dislocation glide in the basal plane (i.e. the GRAPHICS - GRAPHICS plane, where GRAPHICS , GRAPHICS and GRAPHICS define the edge vectors of the unit cell) of GRAPHICS -triamino- GRAPHICS -trinitrobenzene (TATB) using generalized stacking fault energy surfaces ( GRAPHICS -surfaces). Triclinic symmetry and molecular packing arrangement result in two glide plane types for the same glide plane normal. The unstable stacking fault energies ( GRAPHICS ) are less than GRAPHICS GRAPHICS at GRAPHICS K and GRAPHICS atm, indicating easy dislocation glide. Glide in the GRAPHICS and GRAPHICS - GRAPHICS directions is preferred compared to the GRAPHICS direction at GRAPHICS atm. A stable stacking fault is predicted in the GRAPHICS - GRAPHICS direction at GRAPHICS atm and 5GPa. A compound twin with energy GRAPHICS GRAPHICS is predicted to be stable in the basal plane. Unequal values of GRAPHICS about the stable stacking fault in the GRAPHICS and GRAPHICS - GRAPHICS traces indicate an asymmetric barrier to dislocation glide. High pressure ( GRAPHICS GPa) results in an increase in the GRAPHICS values. The extremely small barriers to twinning and dislocation glide might be sources for observed second-harmonic generation in the nominally centrosymmetric crystal.
Return to Publications page