First-principles band gap criterion for impact sensitivity of energetic crystals: a review

Abstract

In this article, we review some recent studies in predicting impact sensitivity for different classes of energetic crystals based on first-principles band gap. Based on these investigations on metal azides, a first-principles band gap criterion is founded to measure impact sensitivity for a series of energetic crystals. For energetic crystals with similar structure or with similar thermal decomposition mechanism, the smaller the band gap is, the easier the electron transfers from the valence band to the conduction band, and the more they becomes decomposed and exploded. Applications of this criterion on other series of energetic crystals show that the first-principles band gap criterion is applicable to different series of energetic crystals with similar structure or with similar thermal decomposition mechanism. This criterion may be useful for molecular design of high-energy density materials.

Structural, vibrational, and quasiparticle band structure of 1,1-diamino-2,2-dinitroethelene from ab initio calculations

“…Earlier, a few theoretical studies using DFT have been made on metal azides as well as organic explosives to understand the correlation between the impact sensitivity and the band gap 54 , they claimed that a small band gap and eases for electron transfer from the valence bands to the conduction bands, which leads eventually to decomposition and explosion. Fig.…”

A first‐principles investigation of the hydrogen bond interaction and the sensitive characters in cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole

“…6 in the crystal phase, compared with the experimental distance 2.233 Å and experimental bond angle 104. 9 . Moreover, the gas-phase BCHMX molecule is closer to the C 1 point group symmetry.…”

“…Zhu and Xiao [9] noted that there is a relationship between the band gap and impact sensitivity for different series of energetic crystals with similar structure or with similar thermal decomposition mechanism. Zhang et al [31] explained well the trend of the impact sensitivity combining the band gap computed from the crystal with the BDE of NO 2 computed from the isolated molecule.…”

“…Hydrogen bonding often leads to highly ordered layering of molecular sheets in solids, which can be an important factor in determining the sensitivity of materials to shocking. In addition, the impact sensitivity is the most important characters, which is associated with the band gap for the crystal [7][8][9] and the dissociation energy of the weakest bond of an explosive molecule [10][11][12][13][14][15][16]. These studies showed that the property of high energetic materials is closely related to the structural and electronic characters of their molecule or crystal.…”

Structural, elastic, optical properties and quasiparticle band structure of solid cyanuric triazide

“…Zhu et al [31] reported that band gaps of azides and explosives, and correlated them with their sensitivity as follows: the smaller the band gap, the easiest it is to transfer an electron from the valence bands to the conduction bands and consequently an external stimuli can more easily decompose the energetic material leading to explosion. Unfortunately, the experimental band gaps are not yet reported for most of these materials, the known band gaps values of inorganic azides (between 1.61 to 4.68 eV for heavy metal azides to light metal azides) and explosives materials (2.37 eV for TATB, 3.62 eV for HMX, 3.55 eV for RDX) are from standard DFT functionals.…”