Structural, vibrational and bonding properties of hydro-nitrogen solids under high pressure: An ab-initio study

Abstract

Hydro-nitrogen solids are potential high energy density materials (HEDMs) due to high mass ratio of nitrogen which find wide range of applications as propellants and explosives. In the present work, we report the structural and vibrational properties of Tetramethyl Ammonium Azide (TMAA) and HydroZonium Azide (HZA) using density functional theory calculations by treating weak intermolecular interactions. The obtained ground state parameters using vdW-TS method are in good agreement with the experimental data. The pressure dependent lattice constants, compressibility and equation of state are discussed. The obtained equilibrium bulk moduli show the soft nature of these materials. The compressibility curves reveal that these compounds are highly compressible along crystallographic a-axis. We have also calculated the zone-center phonon frequencies and made a complete analysis of vibrational spectra at ambient as well as at high pressure. Contraction and elongation of C-H and N-H (NH 3 stretching) bonds under pressure lead to blue-and red-shift of the frequencies in the mid-IR region for TMAA and HZA compounds, respectively.

Compressibility Anisotropy and Electronic Properties of Oxyanionic Hydrates

“…In case when crystals contain molecular complexes taking into account weak intermolecular van der Waals interaction is important. After correction of exchange correlation functional to describe weak intermolecular interactions, DFT can predict the properties for energetic materials, even for alkali-metal nitrates, chlorates and pechlorates anhydrates, that will have good agreement with the experiment. ,,− Over recent years, the study of structures and properties of various materials under hydrostatic compression has been successfully conducted using density functional theory (DFT) method with dispersion correction. ,,− ,− …”