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Sample records for 1,3,5-triamino-2,4,6-trinitrobenzene

  1. A Versatile Synthesis of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, A R; Pagoria, P F; Schmidt, R D; Coburn, M D; Lee, G S; Hsu, P C

    2006-04-06

    A safe and versatile synthesis of high-purity 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) based on vicarious nucleophilic substitution (VNS) chemistry has now been achieved. The starting material can be selected from a variety of inexpensive nitroarenes obtained from commercial suppliers (4-nitroaniline, picric acid) or U.S. stockpiles (ammonium picrate, TNT). The use of picric acid and ammonium picrate (Explosive D) is preferred as both compounds are directly converted to picramide in the presence of ammonium salts (diammonium hydrogen phosphate, ammonium carbamate) in sulfolane at elevated temperature. The picramide resulting from this process is directly converted to TATB using an optimized VNS reaction employing inexpensive hydroxylamine as the nucleophilic aminating reagent. A crucial element in our synthesis is a novel and efficient purification of TATB.

  2. Intermolecular forces and molecular dynamics simulation of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) using symmetry adapted perturbation theory.

    Science.gov (United States)

    Taylor, DeCarlos E

    2013-04-25

    The dimer potential energy surface (PES) of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has been explored using symmetry adapted perturbation theory based on a Kohn-Sham density functional theory description of the monomers [SAPT(DFT)]. An intermolecular potential energy function was parametrized using a grid of 880 ab initio SAPT(DFT) dimer interaction energies, and the function was used to identify stationary points on the SAPT(DFT) dimer PES. It is shown that there exists a variety of minima with a range of bonding configurations and ab initio analyses of the interaction energy components, along with radial cross sections of the PES near each minimum, are presented. Results of isothermal-isostress molecular dynamics simulations are reported, and the simulated structure, thermal expansion, sublimation enthalpy, and bulk modulus of the TATB crystal, based on the SAPT(DFT) interaction potential, are in good agreement with experiment.

  3. Monte Carlo simulations of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB): Pressure and temperature effects for the solid phase and vapor-liquid phase equilibria.

    Science.gov (United States)

    Rai, Neeraj; Bhatt, Divesh; Siepmann, J Ilja; Fried, Laurence E

    2008-11-21

    The transferable potentials for phase equilibria (TraPPE) force field was extended to nitro and amino substituents for aromatic rings via parametrization to the vapor-liquid coexistence curves of nitrobenzene and aniline, respectively. These groups were then transferred to model 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Without any further parametrization to solid state data, the TraPPE force field is able to predict TATB's unit cell lengths and angles at 295 K with mean unsigned percentage errors of 0.3% and 1.8% and the specific density within 0.5%. These predictions are comparable in accuracy to the GRBF model [Gee et al., J. Chem. Phys. 120, 7059 (2004)] that was parametrized directly to TATB's solid state properties. Both force fields are able to reproduce the pressure dependence of TATB's unit cell volume, but they underestimate its thermal expansion. Due to its energetic nature and unusually large cohesive energy, TATB is not chemically stable at temperature in its liquid range. Gibbs ensemble simulations allow one to determine TATB's vapor-liquid coexistence curve at elevated temperatures and the predicted critical temperature and density for the TraPPE and GRBF model are 937+/-8 and 1034+/-8 K, and 0.52+/-0.02 and 0.50+/-0.02 gcm(3), respectively.

  4. Characteristics of energy exchange between inter- and intramolecular degrees of freedom in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with implications for coarse-grained simulations of shock waves in polyatomic molecular crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kroonblawd, Matthew P.; Sewell, Thomas D., E-mail: sewellt@missouri.edu [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600 (United States); Maillet, Jean-Bernard, E-mail: jean-bernard.maillet@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France)

    2016-02-14

    In this report, we characterize the kinetics and dynamics of energy exchange between intramolecular and intermolecular degrees of freedom (DoF) in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). All-atom molecular dynamics (MD) simulations are used to obtain predictions for relaxation from certain limiting initial distributions of energy between the intra- and intermolecular DoF. The results are used to parameterize a coarse-grained Dissipative Particle Dynamics at constant Energy (DPDE) model for TATB. Each TATB molecule in the DPDE model is represented as an all-atom, rigid-molecule mesoparticle, with explicit external (molecular translational and rotational) DoF and coarse-grained implicit internal (vibrational) DoF. In addition to conserving linear and angular momentum, the DPDE equations of motion conserve the total system energy provided that particles can exchange energy between their external and internal DoF. The internal temperature of a TATB molecule is calculated using an internal equation of state, which we develop here, and the temperatures of the external and internal DoF are coupled using a fluctuation-dissipation relation. The DPDE force expression requires specification of the input parameter σ that determines the rate at which energy is exchanged between external and internal DoF. We adjusted σ based on the predictions for relaxation processes obtained from MD simulations. The parameterized DPDE model was employed in large-scale simulations of shock compression of TATB. We show that the rate of energy exchange governed by σ can significantly influence the transient behavior of the system behind the shock.

  5. Characteristics of energy exchange between inter- and intramolecular degrees of freedom in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with implications for coarse-grained simulations of shock waves in polyatomic molecular crystals.

    Science.gov (United States)

    Kroonblawd, Matthew P; Sewell, Thomas D; Maillet, Jean-Bernard

    2016-02-14

    In this report, we characterize the kinetics and dynamics of energy exchange between intramolecular and intermolecular degrees of freedom (DoF) in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). All-atom molecular dynamics (MD) simulations are used to obtain predictions for relaxation from certain limiting initial distributions of energy between the intra- and intermolecular DoF. The results are used to parameterize a coarse-grained Dissipative Particle Dynamics at constant Energy (DPDE) model for TATB. Each TATB molecule in the DPDE model is represented as an all-atom, rigid-molecule mesoparticle, with explicit external (molecular translational and rotational) DoF and coarse-grained implicit internal (vibrational) DoF. In addition to conserving linear and angular momentum, the DPDE equations of motion conserve the total system energy provided that particles can exchange energy between their external and internal DoF. The internal temperature of a TATB molecule is calculated using an internal equation of state, which we develop here, and the temperatures of the external and internal DoF are coupled using a fluctuation-dissipation relation. The DPDE force expression requires specification of the input parameter σ that determines the rate at which energy is exchanged between external and internal DoF. We adjusted σ based on the predictions for relaxation processes obtained from MD simulations. The parameterized DPDE model was employed in large-scale simulations of shock compression of TATB. We show that the rate of energy exchange governed by σ can significantly influence the transient behavior of the system behind the shock.

  6. Theoretical determination of anisotropic thermal conductivity for crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)

    Science.gov (United States)

    Kroonblawd, Matthew; Sewell, Thomas

    2013-06-01

    Bond stretching and three-center angle bending potentials have been developed to extend an existing rigid-bond TATB molecular dynamics (MD) force field (FF) for simulations requiring fully flexible molecules. The FF potentials were fit to experimental vibrational spectra and electronic structure predictions of vibrational normal modes and frequencies using a combination of zero Kelvin eigenmode analysis for the isolated molecule and finite-temperature power spectra for the isolated molecule and bulk crystal. Crystal structures computed using the revised FF are in good agreement with results from other computational models and experimental data. A non-equilibrium MD method was used to obtain the room temperature, atmospheric pressure thermal conductivity along three directions in a well-defined, non-orthogonal basis. The thermal conductivity was found to be significantly anisotropic with values of 1.13 +/- 0.07, 1.07 +/- 0.07 and 0.65 +/- 0.03 W m-1 K-1 for directions nominally parallel to the a, b, and c crystal directions, respectively. The U.S. Air Force Office of Scientific Research supported this research.

  7. Self-deflagration rates of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). [burning tate, thermal stability

    Science.gov (United States)

    Boggs, T. L.; Price, C. F.; Zurn, D. E.; Atwood, A. I.; Eisel, J. L.

    1980-01-01

    The thermal stability and resistance to impact was investigated for the ingredient TABA. Particular attention was given to determining the use of TABA as a possible alternative ingredient or substitute for HMX in explosives and high energy propellants. The burn rate of TABA was investigated as a function of pressure. It was concluded that the self deflagration rate of TABA is an order of magnitude lower than HMX over the range 2000-15000 psi; TABA will not sustain self deflagration at low pressures (less than or equal to 1500 psi) in the sample configuration and apparatus used.

  8. The unusual stability of TATB (1,3,5-triamino-2,4,6-trinitrobenzene): A review of the scientific literature

    Energy Technology Data Exchange (ETDEWEB)

    Rice, S.F.; Simpson, R.L.

    1990-07-04

    This review is intended as an up-to-date review of the scientific literature on TATB since its discovery as a high explosive. In particular, it focuses on clarifying our current understanding of the relationship between the structure of TATB and its unique thermal stability. We review a large number of different publications by many authors. A small portion of the work on TATB'' presented actually consists of experimental studies on TATB formulated as PBX-9502 or as LX-17. Where relevant, this distinction is indicated. However, inasmuch as this review focuses on thermal response and the relationship of chemical reactivity to the molecular and lattice structure of TATB as a pure material, results from these other formulations may not be directly applicable, and in general we have omitted them. 4 refs.

  9. International Annual Conference (29th) of ICT Held in Karlsruhe, Federal Republic of Germany on June 30-July 3, 1998. Energetic Materials; Production, Processing and Characterization

    Science.gov (United States)

    2007-11-02

    Laboratory Los Alamos, New Mexico 87545 ABSTRACT A novel method has been achieved for the preparation of 1,3,5-triamino-2,4,6- trinitrobenzene (TATB) from...HF-Energie in mechanische Schwingungsenergie gleicher Fre- quenz urn. Die dabei erzeugte Amplitude wird Uber eine amplitudenproportionale Frequenz...der die Ausgangsamplitude des Stufenhorns weiter verstdrkt mid Uber eine kleine Endfldche (Durchmesser 6 mm) in das Medium tibertrdgt. Dadurch

  10. New Synthesis of TATB. Scaleup and Product Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, R.D.; Mitchell, A.R.; Lee, G.S.; Pagoria, P.F.; Coburn, M.D.; Quinlan, W.T.; Thorpe, R.; Cates, M.

    2000-03-15

    At the 29th International Annual Conference of ICT (1998), the authors described the results of laboratory-scale process development studies for a new synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). This new synthesis approach--which uses vicarious nucleophilic substitution (VNS) methodology--converts picramide to TATB in high yield, and potentially at lower cost and with few environmental effects than existing synthetic approaches. In this report they describe results of their work on producing TATB by the VNS method at the pilot plant scale. They will discuss structure and control of impurities, changes in yield/quality with reaction conditions, choice of solvents, workup and product isolation, safety, and environmental considerations. Product characterization (particle size, DSC, HPLC, etc.) as well as small-scale safety and performance testing is also discussed.

  11. Conversion of Surplus Picric Acid/Explosive D to Higher Value Products

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, A R; Hsu, P C; Coburn, M D; Schmidt, R D; Pagoria, P F; Lee, G S; Kwak, S S W

    2003-02-28

    The global demilitarization of nuclear and conventional munitions is producing millions of pounds of surplus energetic materials. Historically, energetic materials (high explosives, propellants, and pyrotechnics) have been disposed of by open burning/open detonation (OB/OD). The use of OB/OD is becoming unacceptable due to public concerns and increasingly stringent environmental regulations. Clearly, there is a great need to develop environmentally sound and cost-effective alternatives to OB/OD. The conversion of surplus picric acid and/or ammonium picrate (Explosive D) to 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has been subject of extensive process development studies at Lawrence Livermore National Laboratory (LLNL). LLNL, under the direction and sponsorship of the U.S. Army Defense Ammunition Center (DAC), is developing a process for the conversion of picric acid to TATB on a pilot scale.

  12. Simulative Calculation of Mechanical Property, Binding Energy and Detonation Property of TATB/Fluorine-polymer PBX

    Institute of Scientific and Technical Information of China (English)

    MA, Xiu-Fang; XIAO, Ji-Jun; HUANG, Hui; JU, Xue-Hai; LI, Jin-Shan; XIAO, He-Ming

    2006-01-01

    Molecular dynamics (MD) method was used to simulate 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) coated with fluorine containing polymers. The mechanical properties and binding energies of PBXs were obtained. It was found that when the number of chain monomers of fluorine containing polymers was the same, the elasticity of TATB/F2314 was increased more greatly than others and the binding energy of TATB/F2311 was the largest among four PBXs. Detonation heat and velocity of such four PBXs were calculated according to theoretical and empirical formulas. The results show that the order of detonation heat is TATB>TATB/PVDF>TATB/F2311 >TATB/F2314>TATB/PCTFE while the order of detonation velocity is TATB/PVDF<TATB/F2311 <TATB/F2314<TATB/PCTFE<TATB.

  13. Conversion of Surplus Energetic Materials to Higher Value Products. A New Production of TATB

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, A R; Coburn, M D; Schmidt, R D; Pagoria, P F; Lee, G S

    2002-07-11

    The progression of this project from a general demilitarization activity to the development of a new production of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is described. There are four major synthetic routes to TATB. Only one of these routes has been used in the industrial production of TATB. There is a need to replace this route, which employs relatively harsh reaction conditions (elevated temperatures, strong acid) and a halocarbon starting material, with a less expensive and more environmentally friendly process. The Livermore process, which uses chemistry based on the vicarious nucleophilic substitution (VNS) of hydrogen and employment of relatively inexpensive feedstocks, is described and compared with other routes to TATB. Process development studies and the issue of TATB purification are also discussed.

  14. Recent Progress on the Conversion of Surplus Picric Acid/Explosive D to Higher Value Products

    Energy Technology Data Exchange (ETDEWEB)

    R.Mitchell, A; Hsu, P C; Coburn, M D; Schmidt, R D; Pagoria, P F; Lee, G S; Kwak, S W

    2004-07-06

    The global demilitarization of nuclear and conventional munitions is producing millions of pounds of surplus energetic materials. Historically, energetic materials (high explosives, propellants, and pyrotechnics) have been disposed of by open burning/open detonation (OB/OD). The use of OB/OD is becoming unacceptable due to public concerns and increasingly stringent environmental regulations. Clearly, there is a great need to develop environmentally sound and cost-effective alternatives to OB/OD. The conversion of surplus picric acid and/or ammonium picrate (Explosive D) to1,3,5-triamino-2,4,6- trinitrobenzene (TATB) has been subject of extensive process development studies at Lawrence Livermore National Laboratory (LLNL). LLNL, under the direction and sponsorship of the U.S. Army Defense Ammunition Center (DAC), is developing a process for the conversion of picric acid to TATB on a larger scale. In FY 03, a 10 g per batch process was developed with good results. Development for a one pound per batch system is required as part of overall scale up process for producing TATB from the surplus feedstocks.

  15. Preparation of Ultrafine TATB and the Technology for Crystal Morphology Control%Preparation of Ultrafine TATB and the Technology for Crystal Morphology Control

    Institute of Scientific and Technical Information of China (English)

    Yang, Li; Ren, Xiaoting; Li, Tiecheng; Wang, Shiwei; Zhang, Tonglai

    2012-01-01

    The ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) has been prepared by using solvent and non-solvent method, and the influencing factors in close relationship with the grain size and crystal morphology control such as categories and dosage of surfactants, volume ratio of solvent to non-solvent have also been considered in this paper. It showed that these factors had remarkable effect on the crystal morphology, particle size and agglomeration during the crystallization process. By using 0.095% (mass percentage) ionic surfactant (S) as the additive and using spray-drops feeding device as the dropping equipment, 1.06 g TATB raw materials have been refined into free-running ellipsoid and spherical TATB grains with the grain size from 30 to 50 nm. By using 0.014% (mass percentage) non-ionic surfactant (P) as the additive, spherical TATB grains with the particle diameter of 50 nm and with narrow particle-size distribution have also been obtained. It was shown by the characterizations that the ultrafine particle of TATB had better heat resisting evenness and its 5 seconds ignition point is advanced by 7.5 K.

  16. Detection mechanism of perovskite BFO (1 1 1) membrane for FOX-7 and TATB gases: molecular-scale insight into sensing ultratrace explosives

    Science.gov (United States)

    Bian, Liang; Li, Hai-long; Song, Mian-Xin; Dong, Fa-Qin; Zhang, Xiao-yan; Hou, Wen-ping

    2017-03-01

    Perovskite bismuth ferrite-BFO (1 1 1) membranes, as potential-sensitive electrochemical sensors, are investigated for the detection of high-energy-density materials by molecular dynamics (MD) and density functional theory (DFT) calculations. For the detection mechanism of the sensitive 1, 1-diamino-2, 2-dinitroethylene (FOX-7) gases, both a cation bridge and electrostatic models can be used to explain the STM signatures as 0.02–0.04 V (single) and 0.03~0.05 V (coverage) over a wide range (0–0.1 V) of bias voltages. For insensitive 1, 3, 5-triamino-2, 4, 6-trinitrobenzene (TATB) gases interacting with the surface of a BFO (1 1 1) membrane, the charge signature can be as high as 0.08 V (coverage: 0.06 V). Analysis indicates a significant difference from the detection mechanism observed for FOX-7 gases; that is, the molecularly intact bidentate bridge configuration with only –\\text{NO}2- bonds binds to both Fe and Bi atoms. These differences are attributed so that the surface O2‑ of BFO will capture a part of the surface electron of the –NO2 group, creating a 2p-hole defect (h+) which annihilates a spinning upward (↑) Fe3+, forming a spinning downward (↓) Fe2+. The –NO2 electron decreases 0.35 e (single FOX-7; coverage FOX-7: 0.24 e) and 0.56 e (single TATB; coverage TATB: 0.06 e). Such a system could open up new ideas in the design and application of BFO-based sensors.

  17. Synthesis, Characterization, Thermal Stability and Sensitivity Properties of New Energetic Polymers—PVTNP-g-GAPs Crosslinked Polymers

    Directory of Open Access Journals (Sweden)

    Bo Jin

    2016-01-01

    Full Text Available A series of energetic polymers, poly(vinyl 2,4,6-trinitrophenylacetal-g-polyglycidylazides (PVTNP-g-GAPs, were synthesized via cross-linking reactions of PVTNP with three different molecular weight GAPs using toluene diisocyanate as the cross-linking agent. The structures of these energetic polymers were characterized by ultraviolet visible spectra (UV–Vis, attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR, and nuclear magnetic resonance spectrometry (NMR. The glass-transition temperatures of these energetic polymers were measured with differential scanning calorimetry (DSC method, and the results showed that all the measured energetic polymers have two distinct glass-transition temperatures. The thermal decomposition behaviors of these energetic polymers were evaluated by differential thermal analysis (DTA, thermogravimetric analysis (TGA and thermogravimetric analysis tandem infrared spectrum (TGA-IR. The results indicated that all the measured energetic polymers have excellent resistance to thermal decomposition up to 200 °C, and the initial thermal decomposition was attributed to the breakdown of azide group. Moreover, the sensitivity properties of these energetic polymers were measured with the national military standard methods and their compatibilities with the main energetic components of 2,4,6-trinitrotoluene (TNT-based melt-cast explosive were evaluated by using the DTA method. The results indicate that these energetic polymers have feasible mechanical sensitivities and can be safely used with TNT, cyclotetramethylene tetranitramine (HMX, 1,1-diamino-2,2-dinitroethene (FOX-7, 3-nitro-1,2,4-triazol-5-one (NTO and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB.

  18. ReaxFF-lg: correction of the ReaxFF reactive force field for London dispersion, with applications to the equations of state for energetic materials.

    Science.gov (United States)

    Liu, Lianchi; Liu, Yi; Zybin, Sergey V; Sun, Huai; Goddard, William A

    2011-10-13

    The practical levels of density functional theory (DFT) for solids (LDA, PBE, PW91, B3LYP) are well-known not to account adequately for the London dispersion (van der Waals attraction) so important in molecular solids, leading to equilibrium volumes for molecular crystals ~10-15% too high. The ReaxFF reactive force field is based on fitting such DFT calculations and suffers from the same problem. In the paper we extend ReaxFF by adding a London dispersion term with a form such that it has low gradients (lg) at valence distances leaving the already optimized valence interactions intact but behaves as 1/R(6) for large distances. We derive here these lg corrections to ReaxFF based on the experimental crystal structure data for graphite, polyethylene (PE), carbon dioxide, and nitrogen and for energetic materials: hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX), pentaerythritol tetranitrate (PETN), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and nitromethane (NM). After this dispersion correction the average error of predicted equilibrium volumes decreases from 18.5 to 4.2% for the above systems. We find that the calculated crystal structures and equation of state with ReaxFF-lg are in good agreement with experimental results. In particular, we examined the phase transition between α-RDX and γ-RDX, finding that ReaxFF-lg leads to excellent agreement for both the pressure and volume of this transition occurring at ~4.8 GPa and ~2.18 g/cm(3) density from ReaxFF-lg vs 3.9 GPa and ~2.21 g/cm(3) from experiment. We expect ReaxFF-lg to improve the descriptions of the phase diagrams for other energetic materials.

  19. Modeling the thermal deformation of TATB-based explosives. Part 1: Thermal expansion of “neat-pressed” polycrystalline TATB

    Energy Technology Data Exchange (ETDEWEB)

    Luscher, Darby J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-05-08

    We detail a modeling approach to simulate the anisotropic thermal expansion of polycrystalline (1,3,5-triamino-2,4,6-trinitrobenzene) TATB-based explosives that utilizes microstructural information including porosity, crystal aspect ratio, and processing-induced texture. This report, the first in a series, focuses on nonlinear thermal expansion of “neat-pressed” polycrystalline TATB specimens which do not contain any binder; additional complexities related to polymeric binder and irreversible ratcheting behavior are briefly discussed, however detailed investigation of these aspects are deferred to subsequent reports. In this work we have, for the first time, developed a mesoscale continuum model relating the thermal expansion of polycrystal TATB specimens to their microstructural characteristics. A self-consistent homogenization procedure is used to relate macroscopic thermoelastic response to the constitutive behavior of single-crystal TATB. The model includes a representation of grain aspect ratio, porosity, and crystallographic texture attributed to the consolidation process. A quantitative model is proposed to describe the evolution of preferred orientation of graphitic planes in TATB during consolidation and an algorithm constructed to develop a discrete representation of the associated orientation distribution function. Analytical and numerical solutions using this model are shown to produce textures consistent with previous measurements and characterization for isostatic and uniaxial “die-pressed” specimens. Predicted thermal strain versus temperature for textured specimens are shown to be in agreement with corresponding experimental measurements. Using the developed modeling approach, several simulations have been run to investigate the influence of microstructure on macroscopic thermal expansion behavior. Results from these simulations are used to identify qualitative trends. Implications of the identified trends are discussed in the context of

  20. First-principles study of the phonon sp ectrum and heat capacity of TATB crystal%TATB晶体声子谱及比热容的第一性原理研究∗

    Institute of Scientific and Technical Information of China (English)

    蒋文灿; 陈华; 张伟斌

    2016-01-01

    The widely used energetic material 1, 3, 5-triamino-2, 4, 6-trinitrobenzene (TATB) is an extremely powerful explosive and known for its extraordinary insensitivity to external stimuli (i.e., shock, friction, impact). TATB crystal exhibits graphitic-like sheets with significant inter- and intra-molecular hydrogen bondings within each layer and weak van der Waals (vdW) interactions between layers. Although TATB has been extensively studied both theoretically and experimentally, a fully understanding of its unique detonation phenomenon at a microscopic level is still lacking. Before establishing the exact pathway through which the initial energy is transferred, a fundamental knowledge of both the lattice vibrations (phonons) and molecule internal vibrations must be gained at the first step. Recently, it has been demonstrated that density functional theory (DFT) is inadequate in treating conventional energetic materials, within which dispersion interactions appear to be major contributors to the binding forces. In the present work, phonon spectrum and specific heat of TATB crystal are calculated in the framework of DFT with vdW-DF2 correction, which has been validated in our previous studies of the equation of state, structure and vibration property of TATB crystal under pressures in a range of 0–8.5 GPa. Structure optimization is preformed at zero-pressure, followed by calculating the equation of state, crystal density and lattice energy. The computed results are found to fit well with the experimental and other theoretical values. Frozen phonon method is used to calculate the phonon spectrum and phonon density of states. We find that the phonon density of states reaches its maximum at a vibration frequency of 2.3 THz, which is in good agreement with the strong absorption peak at 2.22 THz observed by THz spectroscopy. The assignment of several Raman active vibrations of TATB above 7.5 THz is given, and a comparison with other published results is also made in this

  1. Atomistic Simulations of Chemical Reactivity of TATB Under Thermal and Shock Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Manaa, M R; Reed, E J; Fried, L E

    2009-09-23

    The study of chemical transformations that occur at the reactive shock front of energetic materials provides important information for the development of predictive models at the grain-and continuum scales. A major shortcoming of current high explosives models is the lack of chemical kinetics data of the reacting explosive in the high pressure and temperature regimes. In the absence of experimental data, long-time scale atomistic molecular dynamics simulations with reactive chemistry become a viable recourse to provide an insight into the decomposition mechanism of explosives, and to obtain effective reaction rate laws. These rates can then be incorporated into thermo-chemical-hydro codes (such as Cheetah linked to ALE3D) for accurate description of the grain and macro scales dynamics of reacting explosives. In this talk, I will present quantum simulations of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystals under thermal decomposition (high density and temperature) and shock compression conditions. This is the first time that condensed phase quantum methods have been used to study the chemistry of insensitive high explosives. We used the quantum-based, self-consistent charge density functional tight binding method (SCC{_}DFTB) to calculate the interatomic forces for reliable predictions of chemical reactions, and to examine electronic properties at detonation conditions for a relatively long time-scale on the order of several hundreds of picoseconds. For thermal decomposition of TATB, we conducted constant volume-temperature simulations, ranging from 0.35 to 2 nanoseconds, at {rho} = 2.87 g/cm{sup 3} at T = 3500, 3000, 2500, and 1500 K, and {rho} = 2.9 g/cm{sup 3} and 2.72 g/cm{sup 3}, at T = 3000 K. We also simulated crystal TATB's reactivity under steady overdriven shock compression using the multi-scale shock technique. We conducted shock simulations with specified shock speeds of 8, 9, and 10 km/s for up to 0.43 ns duration, enabling us to track the