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991.
992.
用密度泛函理论方法研究了镥二聚体(Lu2)低能量电子态的性质,计算了电子态相对能量、平衡键长、振动频率以及基态解离能,考察了密度泛函性质、相对论有效势种类以及Hartree-Fock交换作用大小对计算结果的影响.结果表明,无论采用何种密度泛函和相对论有效势,体系的基态都为三重态,与其他一些基于分子轨道理论的从头计算方法得到的结论是一致的.另外,与分子轨道从头计算结果以及实验结果比较发现,采用杂化密度泛函理论和Stuttgart小核有效势计算得到的结果总体吻合最好.最后,特别分析研究了B3LYP计算中Hartree-Fock交换作用大小对基态键长和基态解离能的影响,发现随着交换作用的增大,键长增长,解离能减小,这是由于5d轨道杂化导致的共价成键作用减弱造成的. 相似文献
993.
A new dielectric slab waveguide with a left-handed material (LHM) cover and substrate is proposed. The dispersion relations
and normalized effective thickness of the asymmetric LHM slab waveguide are investigated, in view of the normalized parameters.
A number of unusual properties are found, for example, the fundamental and first-order modes do not exist and higher-order
modes have double degeneracy. The propagation modes are absent at the low normalized frequency, and the cutoff frequencies
of some LHM slab waveguide modes decrease with increase in the asymmetry measure. Unlike traditional slab waveguides, the
V –H curves of the LHM slab waveguides are in one-to-one correspondence. Both TE and TM modes are discussed; in addition, the
dispersion relations and normalized effective thicknesses of the TM modes are discussed in detail, when the difference in
refractive indices of the film and the substrate is small. The results show that the region of mode coexistence taking place
near the cutoff frequency becomes narrower with increase in the difference in refractive indices of the film and the substrate.
The influence of this difference on the normalized effective thickness curves is different, and becomes smaller and smaller
with increase in the value of the asymmetry measure, if different values of the refractive indices are employed. 相似文献
994.
用Pu的三种不同相对论有效原子实势 (RECP)和密度泛函(B3LYP)方法对PuN基态和低激发态(4Σ+、6Σ+、8Σ+、10Σ+)的分子结构进行了计算,得到了相应的平衡几何构型和谐振频率.采用最小二乘法拟合得到了PuN分子的Murell-sorbie势能函数,在此基础上推导出完整的力常数和光谱数据,并与实验值作对比.结果表明:PuN的基态为X6Σ+,其余为低激发态;在三种RECP中,对于ωe的计算,60个中心电子的SDDRECP/B3LYP给出的结果与实验值符合得比较好(如X6Σ+:ωe=840.77 cm-1,ωeχe=5.73·"cm-1,De=5.880 6 eV,Re=0.176 3 nm,Be=0.408 4 cm-1,αe=3.3E-03 cm-1).计算还给出了相应的电荷布居、自旋密度、电偶极矩和能量特征等系列分子的性质. 相似文献
995.
996.
Bo Qin 《Frontiers of Physics in China》2009,4(1):137-141
Based on the nonlinear oscillation of an air-filled bubble in weakly compressible media at prestressed state, the effective
medium method is used to study the nonlinear property of the slightly compressible media permeated with air bubbles. It is
this nonlinear oscillation of air bubbles that results in the nonlinear property of the porous media. Numerical results have
confirmed that the nonlinearity of the porous media is usually high, though the optimal porosity is very small. Moreover,
the nonlinear property is greatly affected by the prestressed state, porosity, and shear modulus of the matrix media.
相似文献
997.
998.
Spectra and oscillator strengths of 3p63d9--3p53d10 and 3p63d9--3p63d84p transitions for cobalt-like Sn23+ ion
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This paper calculates the spectra and oscillator strengths for highly ionized cobalt-like Sn23+ ions 3p63d9 3p53d10,3p63d9 3p63d84p transitions by using a multi-configuration self-consistent field method program together with the proposed fitting formula.The calculations have a good agreement with observations. 相似文献
999.
Lattice dynamics properties of chalcopyrite ZnSnP_2:Density-functional calculations by using a linear response theory
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We present a first-principles study of the structural,dielectric,and lattice dynamical properties for chalcopyrite semiconductor ZnSnP_2.The structural properties are calculated using a plane-wave pseudopotential method of densityfunctional theory.A linear response theory is used to derive Born effective charge tensors for each atom,dielectric constants in low and high frequency limits,and phonon frequencies.We calculate all zone-center phonon modes,identify Raman and infrared active modes,and report LO-TO splitting of the infrared modes.The results show an excellent agreement with experiment and propose several predictive behaviors. 相似文献
1000.
Air breakdown induced by the microwave with two mutually orthogonal and heterophase electric field components
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The air breakdown is easily caused by the high-power microwave, which can have two mutually orthogonal and heterophase electric field components. For this case, the electron momentum conservation equation is employed to deduce the electric field power and effective electric field for heating electrons. Then the formula of the electric field power is introduced into the global model to simulate the air breakdown. The breakdown prediction from the global model agrees well with the experimental data. Simulation results show that the electron temperature is sensitive to the phase difference between the two electron field components, while the latter can affect obviously the growth of the electron density at low electron temperature amplitudes. The ionization of nitrogen and oxygen induces the growth of electron density, and the density loss due to the dissociative attachment and dissociative recombination is obvious only at low electron temperatures. 相似文献