Understanding the Correlation between Impact Sensitivity and Elasticity of Energetic Crystals via Dispersion-Corrected Density Functional Theory Calculations

Impact sensitivity and elasticity are among the most important properties of energetic materials. Both properties are related to the mechanical stress. Understanding elasticity and impact sensitivity is crucial for predicting the mechanical response and failure of energetic materials, thus establishing a correlation between the elasticity mechanics and the initiation and detonation of energetic materials. However, it is unclear how elasticity influences the impact sensitivity of energetic crystals. Herein, the elastic properties of 19 typical energetic crystals with impact sensitivity varying from low to high are studied by using dispersion-corrected density functional theory. We demonstrate that the elastic stiffness tensors predicted in this work satisfy the necessary and sufficient stability conditions for elastic stability. A thorough comparison with literature data further shows that while the results are in general agreement with literature data, large discrepancies are found for certain elastic tensor elements. By probing the correlation between impact sensitivity and elasticity, we show that higher elastic moduli and elastic anisotropy generally lead to lower impact sensitivity. The underlying mechanism is that higher elastic moduli and higher elastic anisotropy lead to easy absorption of impact energy in the form of elastic deformation and dissipation of impact energy through thermal conductivity and shear sliding, thus lowering the probability of impact-induced formation and growth of hotspots. These findings facilitate our fundamental understanding of the elastic properties and structure–property relationships of energetic crystals.