Generalized stacking fault energies in the basal plane of triclinic molecular crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)

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.