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1.
本文由粘滞系数的时间关联函数表达式,得到了实验观察到的现象:在液晶N相→SA相转变点附近(T→T(sA)),体粘滞系数的反常发散比切变粘滞系数反常发散要大得多。说明了Brochard等人的理论中,不能解释此实验的原因。
关键词: 相似文献
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使用密耦近似(Close-Coupling)方法、采用Tang-Toennies势模型计算了惰性气体原子Ne与H2分子及同位素D2分子在碰撞能量为83.8 meV时的微分散射截面及分波截面, 并与实验值和文献值进行比较.计算得到的微分散射截面值与实验值符合得较好,分波截面值与文献值也相符合.使用同样的方法和模型,文中对Ne-H2(D2,T2)三个体系的微分截面和分波截面进行了系统计算和比较分析,得出对称同位素替代碰撞体系的散射截面规律.
关键词:
2(D2')" href="#">Ne-H2(D2
2)碰撞')" href="#">T2)碰撞
Tang-Toennies势模型
密耦方法
同位素替代 相似文献
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为获取液体介质的声速值,设计了一种测定流体声速的实验方法,该方法利用时差式超声波流量计和标准流量校验设备同时对封闭管道中的液体进行流速测量,分别得到流速的测量值和真实值,从而计算出超声波流量计的仪表系数,并以此导出了一定条件下液体介质的声速值随仪表系数的变化关系式.利用该方法测量给出了0.17 MPa下四氧化二氮(N2O4)在7.6-19.4 ℃、偏二甲肼((CH3)2NNH2)在6.5-25.2 ℃范围内的流体声速值,并为其他液体介质的声速测量提供了借鉴.
关键词:
超声波流量计
声速
仪表系数
温度 相似文献
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本文使用基团理论计算KB5O8·4HO2O(简称KB5)晶体的倍频系数,得到d31=2.61×10-10esu,d32=007×10-10esu,d33=3.26×10-10esu,与实验值符合较好。计算结果表明:氢键对KB5晶体的倍频系数有影响。本文还分析了KB5晶体倍频系数小的起因,除去[B5O6(OH)4]-1基团的微观倍频系数小外,还在于基团的空间排列方式不利,导至最大的微观倍频系数X123相互抵消。最后,本文提出了在含四配位硼原子的硼氧化合物中寻找倍频新材料的结构判据。
关键词: 相似文献
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在忽略电子-声子相互作用的基础上,本文探讨了从能带波函数出发计算AB型晶体倍频系数的可能性。采用计算AB型晶体能带的近似方法——等价轨道法。计算了k=0点的倍频系数,然后通过带宽的修正,使k=0点的倍频系数近似地表为不同k点倍频系数的平均,这一平均值乘以第一布里渊区内k点的总数就是晶体的宏观倍频系数。计算了十七种闪锌矿型和纤维锌矿型晶体的倍频系数,计算值和实验值的吻合相当满意。从中得出几点有用的结论:(1)倍频系数的双能级跃迁模型对闪锌矿型结构是适用的;但对纤维锌矿型结构并不适用。(2)纤维锌矿型晶体的X3332ω系数可表示成两项之和:单重态(Γ1,Γ3)的贡献和双重态(Γ5,Γ6)的贡献。其中单重态对倍频系数贡献正值,双重态贡献负值。(3)使用Pauling的离子性标度fi来表征A—B键的离子性是适宜的。
关键词: 相似文献
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用HFR(Hartree-Fock with relativistic corrections)方法对Rb V—Cd XVI离子4s24p3和4s4p4组态能级结构做了全面系统的理论计算研究. 通过分析能级结构参数的HFR理论计算值与基于实验能级拟合得到的计算值之比值随着原子序数Zc变化的规律,运用广义拟合外推方法预言了这些离子能级结构参数. 由此进一步计算了Rh XⅢ,Pd XIV,Ag XV和Cd XVI离子4s24p3(4S3/2,2P1/2,3/2,2D3/2,5/2)和4s4p4(4P1/2,3/2,5/2,2P1/2,3/2,2D3/2,5/2,2S1/2)组态能级以及电偶极跃迁波长与振子强度. 研究表明,对于4s24p3组态,单组态近似可以得到较满意的结果;而对于4s4p4组态,只有在考虑了4s24p24d的组态相互作用效应时,计算结果的准确性才能明显得到提高. 同时,本文还运用全相对论grasp2K-DEV程序包计算了Rh XⅢ—Cd XVI离子组态能级. 对于Rh XⅢ离子4s24p3(2P1/2),Pd XIV离子4s24p3(4S3/2,2P1/2,3/2,2D3/2,5/2)和4s4p4(2P1/2,3/2,2D3/2,5/2,2S1/2),能级均无实验值;对于Ag XV和Cd XVI离子,截至目前还没实验能级数据,没有实验能级值的所有数据均仅来自本文的计算数值. 本文计算结果与已有实验值吻合得很好. 相似文献
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本文利用量子化学中的多参考组态相互作用方法(MRCI), 在aug-cc-pVQZ级别计算了在环境科学中具有重要作用的离子BP+. 得到了对应三个离解极限B+(1Sg)+P(4Su), B+(1Sg)+P(2Du)以及B+(1Sg)+P(2Pu)的6个Λ-S态势能曲线. 在计算中还考虑了Davidson修正(+Q)和标量相对论效应, 用以提高计算精度. 通过分析Λ-S态的电子结构, 确认了电子态的多组态特性. 计算中首次纳入了旋轨耦合效应, 获得了由BP+离子的6个Λ-S态分裂出的10个Ω 态的势能曲线. 计算得到的势能曲线表明相同对称性的Ω 态的势能曲线存在着明显的避免交叉. 在得到的Λ-S态和Ω 态的势能曲线的基础上, 运用LEVEL8.0程序通过求解核径向的Schrödinger 方程, 得到了相应的Λ-S态和Ω 态的光谱常数Te, Re, ωe, ωeχe, Be和De, 其中基态X4∑-的光谱常数与已有的理论值符合的非常好, 文中其他电子态的光谱常数均为首次报道.
关键词:
多参考组态相互作用方法(MRCI)
势能曲线
光谱常数
旋轨耦合效应 相似文献
12.
Relativistic configuration interaction calculations for the states of
1s22s2,
1s22s3l (l=s,p,d) and
1s22p3l (l=s,p,d) configurations of iron are carried out using relativistic configuration interaction (RCI) and multi-configuration Dirac-Fock (MCDF) method in the active interaction approach. In the present calculation, a large-scale configuration expansion was used in describing the target states. These results are extensively compared with other available calculative and experimental and observed values, the
corresponding present results are in good agreement with experimental and
observed values, and some differences are found with other available
calculative values. Because more relativistic effects are considered than
before, the present results should be more accurate and reliable. 相似文献
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在MRCI+Q/ang-cc-PCVQZ+DK理论基础上对LiAr第一激发态(A2Π)的势能曲线进行了理论计算, 采用HFD(Hartree-Fock dispersion)解析势能函数对得到的势能曲线进行拟合, 并得到了相应的光谱常数, 计算结果与实验值和大部分理论计算值符合得很好. 通过求解核运动的薛定谔方程完整地获得了每个电子态下J=0时的振动能级Ev、转动惯量Bv和6 个离心畸变常数(Dv, Hv, Lv, Mv, Nv, Ov). 然后采用分波法研究了低温及极低温度下激发态Li原子和基态Ar原子沿LiAr相互作用势的弹性碰撞, 在1.0×10- 12 –3.45×10-6 eV碰撞能区内通过数值计算得到了这一弹性碰撞的总截面和各分波截面, 讨论了各分波截面对总截面的影响. 结果表明: 在入射能量低于10-9 eV时弹性散射的总截面值很大且几乎为一常数, 总弹性截面的形状主要由s分波决定, 但是随着碰撞能量的增加, s分波对总截面的贡献不断减少, 高阶分波对散射截面的贡献逐渐增大. 相似文献
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By means of improved ligand-field theory, the “pure electronic” presure-induced shifts (PS's) and the
PS's due to electron-phonon interaction (EPI) of the R1, R2,
B1, B2, B3, and R'3 lines and the ground-state zero-field-splitting of ruby have been uniformly calculated. The calculation results are in very good agreement with all the
experimental data. At normal pressure, ruby is a crystal with very
strong crystal field. Thus, the admixture of
|t22(3T1)e4T2〉and
|t322E〉bases in the wavefunction of R1 level of ruby is small at
normal pressure, and it gradually decreases with increasing pressure, which causes the R1-line PS of ruby to monotonously red shift with approximate linearity. The combined effect of the pure electronic PS of
R1 line and the PS of R1 line due to EPI gives rise to the total PS of R1 line. The analyses and comparisons among the features of R1-line PS's of three laser crystals (ruby,
GSGG:Cr3+ and
GGG:Cr3+) have been made, and the origin of their
difference has been revealed. 相似文献
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A multireference configuration interaction (MRCI) study has been carried out on the LiCl molecule. The potential energy has been calculated over a wide range of internuclear separation for the 21 low-lying electronic states of the LiCl molecule dissociating into Li (2S, 2P, 3S)+Cl(2P). The (4)1Σ+, (3)1Π, 1-33Σ+, 1-33Π, 1,3Δ, 1,3Σ-, (5)1Σ+, (4)3Σ+, (4)1Π, (4)3Π excited states are studied for the first time in theory. Molecular spectroscopic constants (Re, De, ωe, ωeχe, Be and αe) have been derived for the 9 bound states (X1Σ+, (3)1Σ+, (2)1Σ+, 1,3Δ, 1,3Σ-, (4)1Π, (4)3Π) with a regular shape, and the spectroscopic constants of ground states X1Σ+ are in good agreement with available experimental and theoretical values. The relative differences between experimental values and our values for Re, De, ωe, ωeχe, Be and αe are 1.02%, 0.60%, 1.72%, 9.46%, 2.0%, and 0.75%, respectively. Moreover, vibrational levels of 9 bound states, which have not been investigated experimentally, are computed. 相似文献
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本文基于Lee-Low-Pines幺正变换法,采用Tokuda改进的线性组合算符法研究了Rashba自旋-轨道相互作用效应下量子盘中强耦合磁极化子的性质.结果表明,磁极化子的相互作用能Eint的取值随量子盘横向受限强度ω0、外磁场的回旋频率ωc、电子-LO声子耦合强度α和量子盘厚度L的变化均与磁极化子的状态性质密切相关;磁极化子的平均声子数N随ωc,ω0和α的增加而增大,随L的增加而振荡减小;在Rashba自旋-轨道相互作用效应影响下磁极化子的有效质量将劈裂为m*+,m*-两种,它们随ωc,ω0和α的增加而增大,随L的增加而振荡减小;在研究量子盘中磁极化子问题时,电子-LO声子耦合和Rashba自旋-轨道相互作用效应的影响不可忽略,但Rashba自旋-轨道相互作用和极化子效应对磁极化子的影响只有在电子运动的速率较慢时显著. 相似文献
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On the basis of the unified calculation of the thermal shifts of R1 line, R2 line and ground-state-splitting transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings of R, R'and B line-groups for ruby, by taking into account all the levels and admixtures of wavefunctions within d3 electronic configuration and all the ΓM in electron-phonon interaction,the transition probabilities of direct and Raman processes have theoretically been calculated, The thermal broadenings of R,R' and B line-groups have successfully been interpreted in terms of the direct and Raman processes of acoustic phonons. The theoretically predicted transition probabilities are in good agreement with the experimental ones. 相似文献
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Traditional ligand-field theory has to be improved by taking into account
both pure electronic contribution and electron-phonon interaction one
(including lattice-vibrational relaxation energy). By means of improved
ligand-field theory, the R line,
t23 2T1 and t23 2T2
lines, t22 (3T1)e4T2, t22 (3T1)e4T1 and t2
e2(4A2)4T1 bands, g factors of t23 4A2 and t23 2E, four strain-induced level-splittings and R-line thermal shift of
MgO:V2+ have been calculated. The results are in very good agreement with the experimental data. It is found that for
MgO:V2+, the
contributions due to electron-phonon interaction (EPI) come from the
first-order term; the contributions from the second-order and higher terms
are insignificant. In thermal shift of R line of MgO:V2+, the
temperature-dependent contribution due to EPI is dominant. The results
obtained in this work may be used in theoretical calculations of other
effects of EPI. 相似文献
19.
The g factors g||,g⊥ and hyperfine structure constants A||,A⊥ for two trigonal Co^2 centers (i.e.,Co^2 in Cd^2 (I) and Cd^2 (Ⅱ) sites) in CsCdCl3:Co^2 crystals are calculated from the high-order perturbation formulas based on the cluster approach.In the calculation,the contributions from covalency effect and configuration interaction effect are considered and the parameters related to both effects are obtained from the optical spectrum and the structure data of the studied system.The results are in good agreement with the observed values. 相似文献
20.
B~3Σ_u~-态是O_2的最强的三重跃迁(B~3Σ_u~-←XΣ_g~-)Schumann-Runge(SR)带的上态,SR吸收带在保护地球、阻止紫外辐射等方面起着关键作用.SR连续带的光解离是平流层O原子及O_3的主要来源,掌握详细准确的O_2分子的电子态势能曲线,有助于对这些光谱现象的深入理解.本文通过MOLPRO软件,采用包含Davison修正的内收缩的多参考组态相互作用(ic MRCI+Q)方法,对O2的B~3Σ_u~-态的势能曲线进行了计算,采用的多参考组态函数来自完全活性空间自洽场计算.首先,采用共价组态构成多参考组态,对和B~3Σ_u~-态对称性相同的四个态进行了态平均计算,发现B3Σ_u~-态不存在双势阱结构,文献(Spectrochimica Acta Part A:Molecular and Biomolecular Spectroscopy 2014 124 216)中双势阱的产生是根的振荡(root flipping)造成的,即B~3Σ_u~-态的势能曲线在核间距约为0.2 nm处跳变到能量相近的23?态的势能曲线上.本文中的态平均计算避免了这种根的振荡.接着,采用完全活性空间组态相互作用的方法计算B~3Σ_u~-态的势能曲线,通过改变活性空间的轨道组成,发现带有2π_u轨道电子布居的里德伯组态对B~3Σ_u~-态的束缚态的特征的出现是必不可少的.最后,通过将2π_u轨道加入到活性空间中,实现将相关的里德伯组态加入到多参考组态,对B~3Σ_u~-态的势能曲线进行了icMRCI+Q计算,得到相较于以往的理论计算与实验值更加相近的势能曲线以及光谱常数.本文探讨里德伯组态贡献的过程为如何确定多参考组态相互作用计算中的参考组态、提高理论计算的准确度提供了可以借鉴的途径. 相似文献