Theoretical Study on Structures and Stabilities of N7CR (R=H, CH3, NH2, F, Cl) Series
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Abstract The existence of high energetic density material depends more on their kinetic stability. The synthesis reactions of CN 7 – by experimentally known N 3 CN and N 3 – were studied. The barrier of CN 7 – towards dissociation was theoretically calculated as 31.6 kcal⋅mol −1 . The data, calculated at the CCSD(T)//B3LYP/6‐311+G(3df,2p) theoretical level, rised to 38.9 kcal⋅mol −1 when CN 7 H was formed by adding hydrogen anion to CN 7 – , indicating significant improvement in stability. The potential energy surfaces of N 7 C R ( R = CH 3 , NH 2 , F, and Cl) system were also investigated, and the lowest kinetic barrier is 36.3 kcal⋅mol −1 , 35.7 kcal⋅mol −1 , 23.5 kcal⋅mol −1 , and 28.5 kcal⋅mol −1 , respectively. Moreover, the energy gap (E g ) of azidotetrazolates (N 7 C R ) system was calculated by frontier molecular orbital theory to verify the stability.Keywords:
Bond-dissociation energy
Bond-dissociation energy
Radical ion
Bond energy
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The accuracy and effectiveness of various kinetic-energy functionals in providing total noninteracting kinetic energies, atomization kinetic energies, and equilibrium properties is evaluated. Employing converged Kohn-Sham densities, we assess various kinetic-energy functionals in a non-self-consistent manner. It is found that the gradient expansion, the Pearson-Gordon local truncation scheme, and the [4/3]-Pad\'e approximant of DePristo and Kress provide reliable estimates for the total noninteracting kinetic energy. The estimates for the atomization kinetic energy and equilibrium geometries are, however, far from being reliable for chemical applications
Truncation (statistics)
Total energy
Kinetic Theory
Kinetic scheme
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Metastable states in N2O+ and NO2+ have been observed, the product ion of the metastable dissociation being NO+ in each case. In N2O+ (m), with a half-life of ≤0.2×10−6 sec, the total kinetic energy given to the fragments NO+ and N was found to be 1.05±0.05 eV. In NO2+ (m) two processes are found, one of half-life 0.7±0.1×10−6 sec which leads to a total kinetic-energy release of 1.12±0.10 eV, and a second of half-life 2.5±0.5×10−6 sec which leads to a total kinetic-energy release of 0.51±0.10 eV. The effect of pressure on peak height shows the metastable peak from N2O+ to possess a unimolecular component, which, under proper conditions of operation, can be made to predominate over a normally intense collision-induced dissociation peak. The metastable peaks from NO2+ both arise from unimolecular dissociation processes.
Metastability
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An energy diagnostic analysis is applied in the abrupt intensity change stage of super typhoon Saomai(0608),especially concerning the kinetic energy feature.The results show that the total kinetic energy and the rotational kinetic energy(KR) in the lower troposphere increase suddenly during the rapid intensification(RI) stage of the typhoon.Meanwhile,these two kinds of energy in the upper levels significantly decrease while the divergent kinetic energy(KD) rises.The downward transport of the upper tropospheric kinetic energy is a major cause of the RI phenomenon.The conversion of the KR and KD reaches the maximum in the RI stage,kinetic energy for the interaction of divergent wind with rotational wind stays high in the RI stage.Each kinetic energy distribution trend of the whole layer is out-of-phase in a rapid weakening(RW) stage,with an upward transport of the lower tropospheric kinetic energy.There may be a 6 h to 18 h response time for the total kinetic energy and its three components to reach their max.or min.when the RI or RW occurs.
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Intensity
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In this work we studied three dyes which are proposed for potential photovoltaic applications and named Dye7, Dye7-2t and Dye7-3t. The Density Functional Theory (DFT) was utilized, using the M05-2X hybrid meta-GGA functional and the 6–31+G(d,p) basis set. This level of calculation was used to find the optimized molecular structure and to predict the main molecular vibrations, the absorption and emission spectra, the molecular orbitals energies, dipole moment, isotropic polarizability and the chemical reactivity parameters that arise from Conceptual DFT. Also, the pKa values were calculated with the semi-empirical PM6 method.
Triphenylamine
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Density functional theory (DFT) calculations were used to perform the mechanistic studies of CO2 dissociation into CO and O on Ni4, Ni3Pt, and Ni2PtMg clusters. Optimizations of initial, transitional, and final states were performed for all cases. Molecule orbital analysis showed that Pt and Mg possess fine electron donating ability while Ni possesses fine electron accepting ability. CO can chemisorb on all metallic sites and binds more weakly on the Mg atom of a Ni2PtMg cluster, with adsorption energy of -0.42 eV. Energy barrier for CO2 dissociation on Ni4 is 2.07 eV. However, this value can scarcely decease to 1.85 eV when a Pt atom replaces one Ni atom in the Ni4 cluster. The addition of Mg could decrease the energy barrier of CO2 dissociation on the Ni2PtMg cluster without Mg directly involved in the reaction, and the energy barrier decreased to 1.23 eV. When Mg atom is directly involved in the reaction, the energy barrier for CO2 dissociation is as low as 0.48 eV. However, the weak binding energy of CO with Mg is not beneficial to the subsequent reactions. As a result, the addition of Mg and Pt improves the activity of Ni4 cluster for CO2 dissociation, which is consistent with the previous experimental results.
Bond-dissociation energy
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The accuracies of various nonlocal kinetic energy functionals are evaluated by considering the kinetic energies of rare gas atoms and the kinetic energy contributions to the interaction energy (ΔEk) for pairs of rare gas atoms. The most accurate kinetic energy functionals are those that combine the density gradient factors of accurate exchange energy functionals with the Thomas–Fermi (TF) kinetic energy functional; these functionals, including a new one proposed in this paper, give total atomic kinetic energies to within 1%, as well as accurate values of ΔEk. Other gradient-corrected functionals give good results for total kinetic energies, but give poor results for ΔEk.
Mean kinetic temperature
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The mechanism of methane dissociation on an Rh-decorated Ni(100) surface has been investigated Using density functional theory. The study includes the determination of the most stable adsorbate/adsorbent configurations of the species associated with subsequent reactions and generating the energy surface for 𝐶𝐻4 dissociation process. The Rhdecorated Ni(100) surface was found to be more favorable for the process than the NiRh(111) configuration, mainly due to lower the activation energy of 𝐶𝐻 decomposition reaction by 48.5%, leading to a higher conversion of 𝐶𝐻4 to carbon and hydrogen
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Cross sections for reactions of OH−⋅H2O with NO2 are reported for interaction energies from 0.2 to 6 eV. Reactions producing the ions HNO3− and NO2−⋅H2O were observed, in addition to charge transfer and collisional dissociation. These reactions were not observable at an interaction energy of 0.04 eV. Based upon these results, upper and lower bounds for the electron affinity of HNO3 are 0.39⩽E.A. (HNO3)⩽0.73 eV and for the bond dissociation energy of NO2−–H2O are 0.1⩽D(NO2−–H2O) 0.6 eV. It is suggested that the strong energy dependence of the cross sections for the reactions forming HNO−3 and NO2−⋅H2O is the result of dissociation of these ions before detection.
Bond-dissociation energy
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