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    Wyświetlanie 1-5 z 5
    Tytuł:
    Thermochemical and Performance Properties of NO2-Substituted Borazines as New Energetic Compounds with High Thermodynamic Stability
    Autorzy:
    Zamani, M.
    Keshavarz, M. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/951505.pdf
    Data publikacji:
    2014
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    electrostatic potential
    enthalpy sublimation
    enthalpy formation
    density
    Opis:
    The structural isomers of nitroborazines were optimized at M062X/6-311++G** level of theory. The effects of the NO2 group on the molecular volume, molecular surface area, crystal density, positive, negative and total average potentials, variances, average deviation and electrostatic balance parameter on the molecular surface were considered. In addition, some important thermodynamic properties of these compounds, such as gas phase and condensed phase enthalpies of formation (ΔfH° (g) and ΔfH° (c)), and the enthalpy of sublimation (ΔH° sub), were calculated. It was found that the crystal densities (ρ) are in the range 1.4471.902 g/cm3. These values are slightly smaller than the corresponding values of their carbon analogues (except for the mononitro compounds). Meanwhile, the values of ρ for B-substituted, di- and trinitroborazines are larger than the related N-substituted compounds. The calculated values of ΔH° sub are in the range 20.1-30.4 kcal/mol. The calculated values of ΔfH° (g) and ΔfH° (c) for the B-substituted nitroborazines are more negative than those for the N-substituted ones. The stability sequence of the hydrogen bonded network structures of nitroborazines in the condensed phase is: dinitroborazine > mononitroborazine > trinitroborazine. The detonation pressure and velocity of these compounds were also calculated. Nitroborazines can be introduced as energetic compounds with high thermodynamic stability and relatively low detonation performance.
    Źródło:
    Central European Journal of Energetic Materials; 2014, 11, 3; 363-381
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Charge Density Distribution, Electrostatic Properties and Sensitivity of the Highly Energetic Molecule 2,4,6-Trinitro-1,3,5-triazine: A Theoretical Study
    Autorzy:
    Srinivasan, P.
    Maheshwari, K.
    Jothi, M.
    Kumaradhas, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/358320.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    energetic molecule
    electron density
    Laplacian of electron density
    electrostatic potential
    impact sensitivity
    Opis:
    Ab initio and density functional theory (DFT) calculations were carried out on the energetic propellant molecule 2,4,6-trinitro-1,3,5-triazine (TNTA) to understand its bond topology and its energetic properties using the theory of atoms in molecules (AIM). The DFT method predicts that the electron density ρ bcp (r) at the bond critical points of ring C-N bonds is ∼ 2.34 e Å -3 and the corresponding Laplacian ∇ 2 ρ bcp(r) is ∼ -24.4 e Å -5 ; whereas these values are found to be very small in the -NO2 group attached to C-N bonds [ρ bcp(r): ∼ 1.73 e Å -3 and Δ 2 ρ bcp (r): ∼ -14.5 e Å -5 ]. The negative Laplacian values of C-NO 2 bonds are significantly lower which indicates that the charges of these bonds are highly depleted. The C-NO2 bonds exhibit low bond order (∼ 0.8), as well as low (∼ 56.4 kcal/mol) bond dissociation energy. As we reported in our earlier studies, we found high bond charge depletion for these bonds, which are considered the weakest bonds in the molecule. The frontier orbital energies exhibit a wide band gap, which is larger than those of existing molecules TATB, TNT and TNB. The impact sensitivity (H 50 %) (4.2 m) and oxygen balance (2.77%) were calculated and compared with related structures. Large negative electrostatic potential regions were found near the nitro groups where reaction is expected to occur. The relation between charge depletion ∇ 2 ρ bcp(r) and the electrostatic potential at the bond midpoints V mid reveals the sensitive areas of the molecule.
    Źródło:
    Central European Journal of Energetic Materials; 2012, 9, 1; 59-76
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Relationship Between the Heats of Formation and the Molecular Electrostatic Potentials of Polyazaarenes
    Autorzy:
    Bartošková, M.
    Friedl, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/358483.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    high-nitrogen compounds
    azines
    azoles
    heat of formation
    molecular surface electrostatic potential
    Opis:
    In order to characterize the explosive properties of high-nitrogen, energetic compounds, the heats of formation, either in the gas or the solid state, are often used as preliminary data. Their relationship to the number of nitrogen atoms involved is usually known, so exploring it cannot furnish any new information. However, the very promising, quantitative structure property relationship (QSPR) approach utilizes the molecular surface electrostatic potential V(r). We have therefore performed calculations for 12 azines and 10 azoles by the DFT B3PW91/cc-pVTZ method, and constructed their gas phase heats of formation Δf H°(298,g) by means of the isodesmic reaction approach. The acquired gas phase heats of formation Δf H°(298,g) were correlated with the molecular surface electrostatic potentials VS,max, VS,min, and VS(ring), which were calculated by the B3LYP/6-31G(d,p)//B3PW91/cc-pVTZ method. It is shown that the VS(ring) electrostatic potential describes very precisely the structures of high-nitrogen N-heteroaromatics, with both consecutive and isolated nitrogen atoms, and their thermodynamic properties.
    Źródło:
    Central European Journal of Energetic Materials; 2013, 10, 1; 103-112
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal Density Prediction, Charge Density Distribution and the Explosive Properties of the Highly Energetic Molecule 2-Methyl-5-nitramino-tetrazole: a DFT and AIM Study
    Autorzy:
    Srinivasan, P.
    Kumaradhas, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/358115.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    crystal density
    electron density
    Laplacian of electron density
    impact sensitivity
    electrostatic potential
    Opis:
    The ab initio crystal density, bond topological and explosive properties of the energetic molecule 2-methyl-5-nitraminotetrazole (MNAT) have been calculated by the MOLPAK/PMIN software and the AIM theory. The density predicted from the crystal structure simulation almost matches the experimental density. The geometrical parameters of the molecule lifted from the crystal structure are in very close agreement with the reported X-ray molecular structure. The bond topological analysis predicts a signifcantly low bond electron density, as well as a less Laplacian of electron density, for the N–NO2 bond. The Laplacian for the bond to the attached methyl group, the C(2)–N(2) bond, is also found to be less negative; the less negative values of the Laplacian confrms that these are the weakest bonds in the molecule. The impact sensitivity (h50) of the molecule has been calculated, and is almost equal to the reported experimental value. The sensitivity of the molecule was also estimated from the electrostatic imbalance parameter and has the value ν = 0.242. The isosurface of the electrostatic potential of the molecule displays a high negative electrostatic potential region around the tetrazole ring and the nitramine N–N bond, which are the possible reactive locations in the molecule.
    Źródło:
    Central European Journal of Energetic Materials; 2013, 10, 1; 53-68
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystal Structure Prediction and Charge Density Distribution of Highly Energetic Dimethylnitraminotetrazole: a First Step for the Design of High Energy Density Materials
    Autorzy:
    Arputharaj, D. S.
    Srinivasan, P.
    Asthana, S. N.
    Pawar, R. B.
    Kumaradhas, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/358205.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    energetic materials
    crystal structure prediction
    charge density analysis
    atoms in molecules
    electrostatic potential
    Opis:
    The crystal structure of dimethylnitraminotetrazole has been predicted, based on systematically searching for densely packed structures within common organic crystal coordination types, followed by lattice energy minimization. The predicted crystal structures almost match the reported crystal structure determined by X-ray diffraction analysis. To understand the effect of the initial molecular geometry on the crystal packing, the crystal structure simulation was carried out for molecules taken from different environments, such as the X-ray structure (crystal field) and also from ab initiocalculations (gas phase). The predicted crystal structures from both environments are very similar to the reported X-ray structure with a maximum deviation of 4.5%. The crystal density predicted from both methods is close to that reported. The bond topological, energetic and electrostatic properties of the isolated molecule from the predicted crystal structure have been determined using Bader's theory of atoms in molecules. The bond topological characterization reveals that the C-N bond is the weakest bond in the molecule. A large electronegative potential is found in the vicinity of the NO2group and the nitrogen-rich region of the tetrazole ring; these are probably the reactive sites of this molecule.
    Źródło:
    Central European Journal of Energetic Materials; 2012, 9, 3; 201-217
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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