Hirshfeld Surface Method and Its Application in Energetic Crystals

Understanding intermolecular interactions is fundamental to understanding the molecular stacking structures and some properties of energetic crystals, such as density, energy, mechanics, and sensitivity. The Hirshfeld surface method is a straightforward tool to reveal intermolecular interactions and nowadays has become increasingly popular in the field of energetic materials. This article highlights a wide range of applications of this method in describing intermolecular interactions including hydrogen bonding, pi-stacking, halogen bonding, and lone pair-pi (n-pi) stacking, and molecular stacking patterns, and in predicting shear sliding characteristic and further impact sensitivity. Meanwhile, the roughness of the quantitative description of intermolecular interaction strength of the method, as a main shortcoming, is pointed out herein. Thus, this work is expected to guide the right and full use of the method. Besides, we present a perspective about using the Hirshfeld surface method to rapidly screen the molecular stacking mode and further impact sensitivity; thus, the fast screening of the two most important properties can be implemented, in combination with the existing mature energy prediction methods based on components. Thereby, a more reliable prediction procedure with an additional consideration of molecular stacking pattern will be produced, setting a basis for data-driven and crystal engineering research of energetic materials.