Predicting the reactivity of energetic materials: an ab initio multi-phonon approach

Adam A L Michalchuk,Svemir Rudić,Carole A Morrison,Morris Trestman,Peter T Fincham,Colin R Pulham,Peter Portius

doi:10.1039/c9ta06209b

Abstract

The impact sensitivity of energetic materials is successfully predicted using an ab initio model based on the concepts of phonon up-pumping.

Highlights

Energetic materials (EMs; explosives, propellants and pyrotechnics) are characterized by their ability to convert large amounts of chemical potential energy rapidly into kinetic energy
Authors have attempted to correlate bond rupture propensity to the electronic band gap[19] and, in turn, impact sensitivity. As these methods offer only a qualitative rationale for impact sensitivity, they are generally restricted to chemically similar energetic molecules. In view of this restriction, other attempts have included a consideration of the dynamics of a mechanical impact, for example, by studying the effects of stress on band gaps and bond dissociation energies,[20,21,22] or by considering the interlayer energies associated with imposing a structural distortion within the crystal.[23,24]
Due to the inclusion of Gaussian smearing (5 cmÀ1) during generation of the phonon density of states (PDOS), this includes rPe(gso(un)a(mn)c)earbeestwubeesenquneenatrl-yrensoornmanatlizferdeqbuyenÐ dciuesg.(uA).l3l6 values of A numerical example is provided in Electronic supplementary information (ESI) S6 and S7.† This is done in agreement with an indirect up-pumping mechanism, in which up-pumped energy equilibrates across the internal vibrational modes of the material

Summary

Introduction

Approach has culminated in the formulation of dry mixtures, or more commonly, polymer-bonded explosives (PBXs) such as Semtex and C4. As these methods offer only a qualitative rationale for impact sensitivity, they are generally restricted to chemically similar energetic molecules In view of this restriction, other attempts have included a consideration of the dynamics of a mechanical impact, for example, by studying the effects of stress on band gaps and bond dissociation energies,[20,21,22] or by considering the interlayer energies associated with imposing a structural distortion within the crystal.[23,24] These more recent methods have typically been restricted to very small sample sets consisting of only a few EMs. Coffey and Totton,[25] and subsequently Zerilli and Totton,[26] described a mechanism for the localisation of energy in crystalline materials that is based on vibrational energy transfer. From these facts we derive the following series of sensitivity: ABT > HNB > HMX > HBT > FOX-7 > ATZ > NTO z TATB z GTZ z AGTZ z DGTZ

Results and discussion

Conclusions

Preparative procedures and analytical chemistry