Vacancy-induced initial decomposition of condensed phase NTO via bimolecular hydrogen transfer mechanisms at high pressure: a DFT-D study

Abstract

Density functional theory with dispersion-correction (DFT-D) was employed to study the effects of vacancy and pressure on the structure and initial decomposition of crystalline 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (β-NTO), a high-energy insensitive explosive. A comparative analysis of the chemical behaviors of NTO in the ideal bulk crystal and vacancy-containing crystals under applied hydrostatic compression was considered. Our calculated formation energy, vacancy interaction energy, electron density difference, and frontier orbitals reveal that the stability of NTO can be effectively manipulated by changing the molecular environment. Bimolecular hydrogen transfer is suggested to be a potential initial chemical reaction in the vacancy-containing NTO solid at 50 GPa, which is prior to the C-NO2 bond dissociation as its initiation decomposition in the gas phase. The vacancy defects introduced into the ideal bulk NTO crystal can produce a localized site, where the initiation decomposition is preferentially accelerated and then promotes further decompositions. Our results may shed some light on the influence of the molecular environments on the initial pathways in molecular explosives.

Formation and growth mechanisms of natural metastable twin boundary in crystalline β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine: a computational study

“…The distribution of the frontier energy levels reveals the activity of HMX molecules at the internal and external surface. This is in good agreements with previous studies that the surfaces in HMX (crystal surfaces, 4-6 internal vacancies, 3,36,37 and voids 2 ) promote the chemical decomposition of energetic materials. Their studies indicate that the chemical decompositions are more likely to start on the inner and outer surfaces.…”

Initial Decomposition Mechanism of 3-Nitro-1,2,4-triazol-5-one (NTO) under Shock Loading: ReaxFF Parameterization and Molecular Dynamic Study

“…The thermal-induced decomposition kinetic process and burning characteristics of NTO [ 6 , 7 , 8 , 9 , 10 , 11 ] have been studied via various experimental techniques. In addition, the theoretical works concerning the electron structures and possible decomposition paths of NTO [ 12 , 13 , 14 ] were also reported. However, the atom-scale understanding about the shock-induced chemistry reaction of NTO still remain unclear.…”

Surface-Induced Energetics, Electronic Structure, and Vibrational Properties of β-HMX Nanoparticles: A Computational Study

“…Recent advances in theoretical and experimental approaches have made people obtain abundant information about the roles of the surfaces (external surfaces, interfaces, and internal surfaces such as vacancies, voids, etc.) in the decompositions of the energetic materials. ,,− For example, previous ab initio studies presented activation energy and kinetics of decomposition reactions at the surface and internal vacancies for the β- and δ-HMX crystals. , These results confirmed that the surface and vacancy in the bulk altered their decomposition kinetics and mechanisms. Sharia and Kuklja found that the N–NO 2 homolysis of the HMX molecule on the surfaces of β-HMX requires lower activation energy and progresses with an orders of magnitude faster reaction rate than that in the bulk crystal.…”