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91.
Bond dissociation energies for the removal of nitrogen dioxide group in some nit- roalkane energetic materials have been calculated by using the three hybrid density functional theory (DFT) methods B3LYP, B3PW91 and B3P86 with 6-31g** and 6-311g** basis sets. The computed BDEs have been compared with the available experimental results. It is found that the B3P86 method with 6-31g** and 6-311g** basis sets can obtain satisfactory bond dissociation energies (BDEs), which are in extraordinary agreement with the experimental data. Considering the smaller mean absolute deviation and maximum difference, the reliable B3P86/6-311g** method was recommended to compute the BDEs for the removal of nitrogen dioxide group in the nitroalkane energetic materials. Using the method, the BDEs of 8 other nitroalkane energetic materials have been calculated and the maximum difference from experimental value is 1.76 kcal·mol-1 (for the BDE of tC4H9–NO2), which further proves the reliability of B3P86/6-311g** method. In addition, it is noted that the BDEs of C–NO2 bond change slightly for main chain nitroalkane compounds with the maximum difference of only 3.43 kcal mol-1. 相似文献
92.
本文用含时多态展开方法计算了里德堡钾原子在静电场、微波场和低射频场[a radio-frequency(rf)field]共同作用下方波振荡的激发特性.研究计算了通过改变微波场的频率、振幅和静电场的振幅以及用低射频锯齿波代替低射频余弦波后方波振荡的变化,获得了一些非常有趣的结果,并给出了理论解释. 相似文献
93.
We demonstrate theoretically that Li atoms can be transferred to states of a lower principal quantum number by exposing them to a frequency chirped microwave pulse. The population transfer of Li atoms from the n = 75 state to n = 70 with more than 90% efficiency is achieved by means of the sequential single-photon △n = -1 transitions. The calculation fully utilizes all of the available orbital angular momentum l states for a given n, and the interference pattern and population evolution dynamics of individual l states are analyzed in detail. Using the time-dependent multilevel approach, we describe the process reasonably well as a sequence of adiabatic rapid passages. 相似文献
94.
The plane-wave pseudopotential method using the generalized gradient approximation within the framework of density functional theory is applied to analyse the lattice parameters, elastic constants, bulk moduli, shear moduli and Young's moduli of WSi2. The quasi-harmonic Debye model, using a set of total energy versus cell volume obtained with the plane-wave pseudopotential method, is applied to the study of the elastic properties and vibrational effects. The athermal elastic constants of WSi2 are calculated as a function of pressure up to 35 GPa. The relationship between bulk modulus and temperature up to 1200 K is also obtained. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs function. The calculated results are in good agreement with the experimental data. 相似文献
95.
Using a time-dependent multilevel approach, we demonstrate
that lithium atoms can be transferred to states of lower principle
quantum number by exposing them to a frequency chirped microwave
pulse. The population transfer from n = 79 to n = 70 states of
lithium atoms with more than 80% efficiency is achieved by means
of the sequential two-photon Δ n = - 1 transitions. It is
shown that the coherent control of the population transfer can be
accomplished by the optimization of the chirping parameters and
microwave field strength. The calculation results agree well with
the experimental ones and novel explanations have been given to
understand the experimental results. 相似文献
96.
97.
With nonlinear Mach-Zehnder interferometer (NLMZI) and a typed beta-barium borate (BBO) crystal, we optically generate single-mode excited entangled coherent states. This scheme can be easily generalized to generate two-mode excited entangled coherent states. We simply analyse different influences of single- and two-mode photon excitations on entangled coherent states. 相似文献
98.
99.
从第一原理出发,利用密度泛函理论B3LYP系统研究了碳分子线Cn(n=3~10)的电子结构特性.对优化结果分析发现,由于离域效应的作用,当n为奇数时,分子线基态为单重态,反之,当n为偶数时,三重态为其稳定的基态.对其电子结构分析可得,随着n的增加,体系能量逐渐降低;同时本文确定了分子线体系最高占据轨道HOMO能量E^H、最低未占据轨道LUMO能量E^L与n的关系式,即En-2^H〈En^H〈En+2^H,En-2^L〉En^L〉En+2^L,因而碳分子线的费米能级会表现出特有的奇偶性.该工作将有利于准确认识分子器件的伏安特性,设计出良好性能的分子器件。 相似文献
100.