Assessment of Dispersion Corrected Atom Centered Pseudopotentials: Application to Energetic Molecular Crystals

High pressure structural behaviour of 5,5'-bitetrazole-1,1'-diolate based energetic materials: a comparative study from first principles calculations

Pressure on the scale of gigapascals can cause incredible variations in the physicochemical and detonation characteristics of energetic materials. As a continuation of our earlier work (B. Moses Abraham, et al., Phys. Chem. Chem. Phys., 2018, 20, 29693–29707), here we report the high pressure structural and vibrational properties of 5,5′-bitetrazole-1,1′-diolate based energetic ionic salts via dispersion-corrected density functional theory calculations. Remarkably, these energetic materials exhibit anisotropic behavior along three crystallographic directions with progressing pressure; especially, the maximum and minimum reduction in volume is observed for HA-BTO and TKX-50, respectively. The large bulk modulus of TKX-50 (28.64) indicates its hard nature when compared to other BTO-based energetic salts. The effect of pressure on hydrogen bonded D–H⋯A energetic materials induces spectral shift (lengthening/shortening) in the donor group (D–H) of the stretching vibrations and is widely recognized as the signature of hydrogen bonding. We observed unusual contraction of the D–H bond under compression due to the short range repulsive forces encountered by the H atom while the molecule attempts to stabilize. The Hirshfeld surface analysis highlights the pressure induced stabilization of HA-BTO due to increased N⋯H/H⋯N and O⋯H/H⋯O close contact of hydrogen bond acceptors and donors. These studies provide theoretical guidance as a function of pressure, on how the micro-structures and intermolecular interactions can tune macroscopic properties to enhance the energetic performance.

We report the high pressure structural and vibrational properties of 5,5′-bitetrazole-1,1′-diolate based energetic ionic salts via dispersion-corrected density functional theory calculations.

Modeling Polymorphic Molecular Crystals with Electronic Structure Theory

Interest in molecular crystals has grown thanks to their relevance to pharmaceuticals, organic semiconductor materials, foods, and many other applications. Electronic structure methods have become an increasingly important tool for modeling molecular crystals and polymorphism. This article reviews electronic structure techniques used to model molecular crystals, including periodic density functional theory, periodic second-order Møller-Plesset perturbation theory, fragment-based electronic structure methods, and diffusion Monte Carlo. It also discusses the use of these models for predicting a variety of crystal properties that are relevant to the study of polymorphism, including lattice energies, structures, crystal structure prediction, polymorphism, phase diagrams, vibrational spectroscopies, and nuclear magnetic resonance spectroscopy. Finally, tools for analyzing crystal structures and intermolecular interactions are briefly discussed.