Interplay of Decomposition Mechanisms at Shear-Strain Interface

Understanding the structure and properties of buried interfaces in materials and devices is a great challenge in physics, chemistry, and materials science. Here we present density functional theory (DFT) based simulations of interfaces in a diamino-dinitroethylene (DADNE, C2H4N4O4) molecular crystal. It is shown that interfaces formed in this material by shear-strain deformations affect the energies and activation barriers of DADNE decomposition and that they may be responsible for triggering explosive decomposition in the crystal. Individual molecules located at the interfaces exhibit lowered activation barriers for structural transformations and decomposition processes, which prompts them to serve as nucleation sites for the overall decomposition of the material possibly leading to a chain reaction and explosion. These results shed light on the molecular nature of the localized hot spots in energetic materials and may provide recommendations for rational design of new materials with tailored properties.