Dispersion Corrected Structural Properties and Quasiparticle Band Gaps of Several Organic Energetic Solids

Appalakondaiah, S.; Vaitheeswaran, G.; Lebègue, Sébastien

doi:10.1021/acs.jpca.5b04233

Cited by 22 publications

(18 citation statements)

References 74 publications

(159 reference statements)

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“…The bulk moduli of TEX calculated from the pressure–volume data obtained from high-pressure XRD using the third-order Birch–Murnaghan equation are B 0 = 9 GPa for the ambient α-phase and B 0 = 15 GPa for the α′-phase. These values are comparable to experimental results on CL-20 ( B = 14 GPa) and computed values for TEX (13.5–20.6 GPa) …”

Section: Phase Transitions In Some Important Secondary Explosivessupporting

confidence: 90%

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

2019

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Under ambient conditions, energetic materials may exist in one or more than one metastable crystal structure. Under compression or when heated, the material may transform into a different structure or may decompose. Mapping the phase diagram of explosive materials at high pressures and temperatures is an important component to evaluate their performance and safety aspects. In particular, a detailed knowledge of polymorphism and the structural and chemical stabilities of the various phases is necessary to understand the reactive behavior of explosive materials in the high-pressure and high-temperature range that is relevant to shock-wave initiation. Phase transformations could be rate-dependent; that is, fast compression or rapid heating could result in different transformation pressures, temperatures, or even structures compared with static compression and slow heating because shock compression could be accompanied by sudden and extreme heating effects. Nevertheless, static methods are expected to give a fair idea of the structure of the materials under different P–T conditions and, from the structure, their performance characteristics. Also, the shock-wave physics and chemistry of explosives are so complex that in shock experiments it has not been possible to identify the intermediate phases of molecules during decomposition. Hence experiments with static high pressure and high temperature are necessary to gain insight into these processes. Additionally, computational modeling and simulations have been extensively used to understand the effects of pressure on explosives. There is considerable literature on these aspects of energetic materials accumulated over the years. We will review the current status of experimental results, primarily using X-ray diffraction, Raman, and infrared spectroscopies, as probes exploring the P–T phase diagram of important secondary explosives ammonium nitrate, TNT, TATB, PETN, RDX, HMX, CL-20, TEX, FOX-7, and TKX-50.

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Section: Phase Transitions In Some Important Secondary Explosivessupporting

confidence: 90%

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

2019

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“…In these crystal structures, van der Waals interactions are the dominant contributions to intermolecular interactions. Hence, it is essential to consider dispersion correction for first principal calculations of energetic solids. − …”

Section: Resultsmentioning

confidence: 99%

Molecular-Shape-Dominated Crystal Packing Features of Energetic Materials

Liu¹,

Cao²,

Lai³

et al. 2021

Crystal Growth & Design

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Molecular shape is observed to greatly determine the properties of energetic materials (EMs); that is, the spherical molecules generally have high energy while the planar molecules have low sensitivity in common. Nevertheless, how the molecular shapes along with their packing modes affect the crystal packing features, such as crystal density and packing coefficient (PC), that are crucial factors describing the energy and sensitivity properties of EMs, is still unclear. Herein, this issue was addressed via a statistical analysis of more than 103 available energetic crystals. Despite crystal density having an overall increasing trend with PC, high crystal density and high PC are dominated by spherical and planar molecules, respectively. Intra- and intermolecular hydrogen bonds are important factors that affect molecular shapes and packing features of EMs, respectively. Hopefully, the results reported here can deepen the understanding of the structure–property relationship to rationally design novel EMs with outstanding properties. Moreover, the present study provides a route to quantitatively identify the molecular shapes and packing modes based on simple structural parameters, which can be further applied to the detailed identification and analysis of energetic crystals with specific packing modes.

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“…This clearly represents that the standard PBE-GGA functional is inadequate to predict the ground state properties of the energetic layered and molecular solid MF. Recently, usage of non-local correction methods become successful in describing the structural properties of energetic molecular solids, 25,[38][39][40] nitrogen rich salts, 41 organic-inorganic hybrid perovskite, 42,43 and layered materials. 44 With this motivation, we have also used various non-empirical dispersion corrected methods to capture vdW interactions to reproduce the ground state properties which are comparable with the experiment.…”

Section: Resultsmentioning

confidence: 99%

Structural, electronic and optical properties of well-known primary explosive: Mercury fulminate

Yedukondalu

Vaitheeswaran

2015

The Journal of Chemical Physics

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Mercury Fulminate (MF) is one of the well-known primary explosives since 17th century and it has rendered invaluable service over many years. However, the correct molecular and crystal structures are determined recently after 300 years of its discovery. In the present study, we report pressure dependent structural, elastic, electronic and optical properties of MF. Non-local correction methods have been employed to capture the weak van der Waals interactions in layered and molecular energetic MF. Among the non-local correction methods tested, optB88-vdW method works well for the investigated compound. The obtained equilibrium bulk modulus reveals that MF is softer than the well known primary explosives Silver Fulminate (SF), silver azide and lead azide. MF exhibits anisotropic compressibility (b > a > c) under pressure, consequently the corresponding elastic moduli decrease in the following order: C22 > C11 > C33. The structural and mechanical properties suggest that MF is more sensitive to detonate along c-axis (similar to RDX) due to high compressibility of Hg⋯O non-bonded interactions along that axis. Electronic structure and optical properties were calculated including spin-orbit (SO) interactions using full potential linearized augmented plane wave method within recently developed Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. The calculated TB-mBJ electronic structures of SF and MF show that these compounds are indirect bandgap insulators. Also, SO coupling is found to be more pronounced for 4d and 5d-states of Ag and Hg atoms of SF and MF, respectively. Partial density of states and electron charge density maps were used to describe the nature of chemical bonding. Ag-C bond is more directional than Hg-C bond which makes SF to be more unstable than MF. The effect of SO coupling on optical properties has also been studied and found to be significant for both (SF and MF) of the compounds.

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Dispersion Corrected Structural Properties and Quasiparticle Band Gaps of Several Organic Energetic Solids

Cited by 22 publications

References 74 publications

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

Molecular-Shape-Dominated Crystal Packing Features of Energetic Materials

Structural, electronic and optical properties of well-known primary explosive: Mercury fulminate

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