Twin Induced Sensitivity Enhancement of HMX versus Shock: A Molecular Reactive Force Field Simulation

Wen, Yushi; Xue, Xiangxin; Zhou, Xiaoqing; Guo, Feng; Long, Xinping; Zhou, Yang; Li, Hongzhen; Zhang, Chaoyang

doi:10.1021/jp4072795

Cited by 57 publications

(68 citation statements)

References 29 publications

(55 reference statements)

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“…Instead of simulating a shock wave within a large computational cell with many atoms, the computational cell of the MSST method follows a Lagrangian The Journal of Physical Chemistry B Article point through the shock wave, enabling the simulation of the shock wave with really fewer atoms and significantly lower computational cost. This technique had been successfully tested on simulating of NM, 35 TATB, 36 and HMX 20,23,29,37 under the shock wave loading and shown to be an accurate prediction of physical and chemical behaviors.…”

Section: Computational Detailsmentioning

confidence: 99%

Dynamic Responses and Initial Decomposition under Shock Loading: A DFTB Calculation Combined with MSST Method for β-HMX with Molecular Vacancy

Ji²,

Liu

et al. 2015

J. Phys. Chem. B

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Despite extensive efforts on studying the decomposition mechanism of HMX under extreme condition, an intrinsic understanding of mechanical and chemical response processes, inducing the initial chemical reaction, is not yet achieved. In this work, the microscopic dynamic response and initial decomposition of β-HMX with (1 0 0) surface and molecular vacancy under shock condition, were explored by means of the self-consistent-charge density-functional tight-binding method (SCC-DFTB) in conjunction with multiscale shock technique (MSST). The evolutions of various bond lengths and charge transfers were analyzed to explore and understand the initial reaction mechanism of HMX. Our results discovered that the C-N bond close to major axes had less compression sensitivity and higher stretch activity. The charge was transferred mainly from the N-NO2 group along the minor axes and H atom to C atom during the early compression process. The first reaction of HMX primarily initiated with the fission of the molecular ring at the site of the C-N bond close to major axes. Further breaking of the molecular ring enhanced intermolecular interactions and promoted the cleavage of C-H and N-NO2 bonds. More significantly, the dynamic response behavior clearly depended on the angle between chemical bond and shock direction.

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Section: Computational Detailsmentioning

confidence: 99%

Dynamic Responses and Initial Decomposition under Shock Loading: A DFTB Calculation Combined with MSST Method for β-HMX with Molecular Vacancy

Ji²,

Liu

et al. 2015

J. Phys. Chem. B

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“…The computational cell could be simulated with fewer atoms and lower computational cost by following a Lagrangian point through the shock wave. [14] Currently, the molecular dynamics method based on MSST have been applied in HMX [15] , TATB [16] , and graphite [17] and so on. In this work we report DFTB-MD simulation of the shock Hugoniot of water, using MSST module in LAMMPS [18] in conjunction with DFTB+ [19] 0 and δ=90 0 .…”

Section: Computational Detailsmentioning

confidence: 99%

DFTB-MD Simulation of Shocked Water Cluster

Liu¹,

Zhou²,

Li³

et al. 2016

Proceedings of the 2016 5th International Conference on Advanced Materials and Computer Science

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Abstract.Relatively efficient and precise quantum molecular dynamics simulations were performed to gain fundamental insights into the mechanisms for the primary detonation process of water under shock wave loading using self-consistent charge density-functional tight binding (SCC-DFTB) calculations combined with the multiscale shock technique (MSST) as well as DFTB+ program conjunct with MSST. We observe that water achieves chemical equilibrium in less than 4ps for all shock conditions studied. What's more, we make comparison with the experimental results for the Hugoniot pressure and density final states. At last, our simulations show that decomposition occurs through the reversible H 2 O↔H + +OH -, in agreement with experiment. Therefore, the molecular dynamics method of water under extreme conditions is effective.

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“…Wen et al [43] used ReaxFF-MD to demonstrate that twinned HMX crystals are much more shock sensitive than perfect HMX crystals. Long and Chen [16] studied the reaction kinetics of HMX by using ReaxFF-MD and observed that the detonation velocity and pressure agreed very well with experimental results.…”

Section: Introductionmentioning

confidence: 99%

Study of thermal instability of HMX crystalline polymorphs with and without molecular vacancies using reactive force field molecular dynamics

Moxnes¹,

Jensen²,

Unneberg³

2016

astp

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The sensitivity of energetic materials can be identified by heat, friction, impact, shock, electrostatic charge, etc. A complexity of various factors may influence the sensitivity and among them are the crystal structure and the defects within the crystal very important. The explosive octahydro-1,3,5,7-tetranitro-1,3,5,7tetrazocine (HMX) may exist in four crystalline polymorphs, denoted α, β, γ, and δ. It has been shown that β-HMX has the lowest impact sensitivity of them whereas δ-HMX has the highest, and that the density of the polymorphs decreases with increasing sensitivity. Knowledge and understanding of the relationship between polymorphism and chemical decomposition processes in crystalline HMX phases may enable improvement of existing energetic compounds or development of novel materials. Thermal instability may be strongly related to mechanical instability due to hot-spot mechanisms. In this work we apply reactive force field molecular dynamics (ReaxFF-MD) to study how the thermal stability of α-and β-HMX is affected by crystalline structure, molecular vacancies, and density. We have found decomposition temperatures of around 1550 K for both * Corresponding author 332 John F. Moxnes et al. polymorphs, which is significantly higher than experimental results of around 550 K. However, by introducing molecular vacancies into the crystals the decomposition was calculated to occur at 400-600 K, in agreement with experimental values. The α polymorph was more sensitive than the β polymorph when vacancies were present. We also discovered that the β polymorph had better resistance against rupture of the N-NO2 bond at higher crystal densities. These results may hint on the different impact sensitivity of the two polymorphs and highlight the influence of crystal structure, crystal defects, density, and temperature on the sensitivity.

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Twin Induced Sensitivity Enhancement of HMX versus Shock: A Molecular Reactive Force Field Simulation

Cited by 57 publications

References 29 publications

Dynamic Responses and Initial Decomposition under Shock Loading: A DFTB Calculation Combined with MSST Method for β-HMX with Molecular Vacancy

Dynamic Responses and Initial Decomposition under Shock Loading: A DFTB Calculation Combined with MSST Method for β-HMX with Molecular Vacancy

DFTB-MD Simulation of Shocked Water Cluster

Study of thermal instability of HMX crystalline polymorphs with and without molecular vacancies using reactive force field molecular dynamics

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