Static electric dipole polarizability of lithium atoms in Debye plasmas

<正>The static electric dipole polarizabilities of the ground state and n≤3 excited states of a lithium atom embedded in a weekly coupled plasma environment are investigated as a function of the plasma screening radium.The plasma screening of the Coulomb interaction is described by the Debye-H（u|¨）ckel potential and the interaction between the valence electron and the atomic core is described by a model potential.The electron energies and wave functions for both the bound and continuum states are calculated by solving the Schrodinger equation numerically using the symplectic integrator.The oscillator strengths,partial-wave,and total static dipole polarizabilities of the ground state and n≤3 excited states of the lithium atom are calculated.Comparison of present results with those of other authors, when available,is made.The results for the 2s ground state demonstrated that the oscillator strengths and the static dipole polarizabilities from np orbitals do not always increase or decrease with the plasma screening effect increasing, unlike that for hydrogen-like ions,especially for 2s→3p transition there is a zero value for both the oscillator strength and the static dipole polarizability for screening length D = 10.3106a₀,which is associated with the Cooper minima.     

Sc+18离子1s23d-1s2nf的跃迁能和偶极振子强度

用全实加关联方法计算了类锂Sc 18离子1s23d-1s2nf(4≤n≤9)的跃迁能和1s2nf(n≤9)态的精细结构。依据量子亏损理论确定了该Rydberg系列的量子数亏损,用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≥10)的能量可靠的预言。利用在计算能量过程中确定的波函数,计算了Sc 18离子1s23d-1s2nf的偶极跃迁在三种规范下振子强度;将这些分立态振子强度与量子亏损理论相结合,得到在电离阈附近束缚态-束缚态跃迁振子强度以及束缚态-连续态跃迁振子强度密度,从而将Sc 18离子的这一重要光谱特性的理论预言外推到整个能域。     

Oscillator strengths for 2 ^2P-n ^2D transitions of lithium-like systems with Z=11 to 20

The dipole-length, velocity and acceleration absorption oscillator strengths for the 1s^22p－1s^2nd(3≤n≤9) transitions of the lithium-like systems with Z=11 to 20 are calculated using the energies and the multiconfiguration interaction wavefunctions obtained from a full core plus correlation method. The agreement between the f-values calculated from the length, velocity and acceleration formulae is excellent. Our results agree closely with the experimental data available in the literature. Combining these discrete oscillator strengths with the single-channel quantum defect theory, the discrete oscillator strengths for the transitions from 1s^22p state to highly excited states (n≥10) and the oscillator strength densities corresponding to the bound-free transitions are obtained.     

Cr~(21+)离子1s~23d-1s~2nf的跃迁能和偶极振子强度(英文)

用全实加关联方法计算了类锂Cr21+离子1s23d-1s2nf(4≤n≤9)的跃迁能和1s2nf(n≤9)态的精细结构.在类氢近似下估算了对能量的高阶相对论修正.依据量子亏损理论,确定了Rydberg系列1s2nf的量子数亏损.据此可以实现对任意高激发态(n≥10)的能量的可靠预言.计算了Cr21+离子1s23d-1s2nf(4≤n≤9)跃迁的振子强度.与量子亏损理论相结合,得到该离子从1s23d态到电离阈附近高激发束缚态间的偶极跃迁振子强度以及到相应连续态跃迁的振子强度密度,从而将Cr21+离子的这一重     

Direct and interwell excitons in magnetic nanostructures

The energies of direct and interwell excitons in superlattices based on europium and lead sulfides have been calculated. It is established that these excitons have higher oscillator strengths and binding energies due to the indirect exchange. This circumstance can be used in semiconductor devices operating on exciton transitions.     

Transition energy and dipole oscillator strength for 1s22p-1s2nd of Cr2l+ ion

The transition energies, wavelengths and dipole oscillator strengths of 1s^22p-1s^2nd （3 ≤ n ≤ 9） for Cr^21＋ ion are calculated. The fine structure splittings of 1s^2nd （n ≤ 9） states for this ion are also calculated. In calculating energy, we have estimated the higher-order relativistic contribution under a hydrogenic approximation. The quantum defect of Rydberg series 1s^2nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experimental data available in the literature. Combining the quantum defect theory with the discrete oscillator strengths, the discrete oscillator strengths for the transitions from initial state 1s^22p to highly excited 1s^2nd states （n ≥ 10） and the oscillator strength density corresponding to the bound-free transitions are obtained.     

Radiative transitions in highly ionised silicon-like ions

Transition energies, oscillator strengths and transition probability values for radiative transitions have been calculated for the highly ionised atoms of Si isoelectronic sequence from Mn¹¹⁺ to Kr²²⁺ for the singly excited states up to principal quantum number n = 7. Time-dependent coupled Hartree-Fock (TDCHF) theory has been used to estimate such transition properties. Most of the results for the oscillator strengths and transition probabilities are new. Transition energies agree reasonably well with available spectroscopic values. Received 25 January 2000 and Received in final form 24 October 2000     

A comparative study of the ion-sphere and debye-huckel potentials

Numerical eigenvalues, critical screening lenghts, and bound-bound dipole oscillator strengths have been computed using an ion-sphere potential (ISP) and compared with those computed using the Debye-Huckel potential (DHP). Although the ISP supports a significantly smaller number of bound levels than the DHP, the highest excited states for both potentials have binding energies which are smaller than plasmon energies. Therefore, collective atomic transitions in dense plasmas involving excited states of these screened Coulomb potentials are energetically allowed.     

V+20离子的能量和偶极振子强度

用全实加关联方法计算了类锂V+20离子 1s2nl(l=s,p, d;n≤9) 态的电离势和精细结构.依据单通道量子亏损理论, 确定了这三个Rydberg系列的量子数亏损.用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≥10)的能量的可靠预言.用在计算能量过程中确定的波函数,计算了V+20离子1s22s-1s2np及1s22p-1s2nd (n≤9)跃迁的振子强度.将这些分立态振子强度与单通道量子亏损理论相结合,得到在电离域附近束缚态间的偶极跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而将V+20离子的这一重要光谱特性的理论预言外推到整个能域.     

Mn22+离子1s22s-1s2np的偶极跃迁能和振子强度

用全实加关联方法计算了类锂Mn22 离子1s22s-1s2np(2≤n≤9)的偶极跃迁能和振子强度.1s2np(2≤n≤9)态的精细结构通过计算自旋-轨道与自旋-其他轨道相互作用算符的期待值确定.依据单通道量子亏损理论,确定了Rydberg系列1s2np的量子数亏损.从而可以用这些作为能量的缓变函数的量子亏损,实现对任意高激发态(n≥10)的能量的可靠预言.将这些分立态振子强度与单通道量子亏损理论相结合,得到在电离阈附近束缚态-束缚态跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而将Mn22 离子的这一重要光谱特性的理论预言外推到整个能域.     

Relativistic energies and transition probabilities for some highly excited levels in singly ionized indium

For some excited levels (n?8), the energies, wavelengths, oscillator strengths and transition probabilities calculations in singly ionized indium have been calculated within the framework of multiconfiguration Hartree-Fock approximation with relativistic corrections (Breit-Pauli Hamiltonian). The wavefunctions and some relativistic corrections have been obtained using MCHF-BP atomic package. Comparisons with other calculations and experiments are presented.     

Excited State Properties of Fluorine-Substituted Hexabenzocoronene: A Quantum-Chemical Characterization

The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett.7 (2005) 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene.     

二氢化钚分子激发态结构的外场效应

采用密度泛函(DFT)方法B3LYP/Gen，在Pu为SDD基组、H为6-311++G^**基组水平上优化得到了分子轴方向不同电偶极场(-0.005—0.005a.u.)作用下，二氢化钚的基态电子状态、几何结构、电偶极矩和分子总能量.在优化构型下用同样的基组采用含时密度泛函(TDDFT)方法(TD-B3LYP)研究了同样外电场条件下对二氢化钚的激发能和振子强度的影响.计算结果表明，分子几何构型与电场大小和方向呈现较强的依赖，电场强度增加基态偶极矩随电场强度线性增加，H-Pu-H的角度线性减小，分子总能量线性减小；激发能随电场强度增加而减小，且对电场方向的依赖呈现近似对称性，满足Grozema关系.电场对振子强度的影响比较复杂，但仍满足跃迁选择定则. 关键词： 二氢化钚 激发态 电偶极场 TD-DFT     

Excited State Properties of Fluorine-Substituted Hexabenzocoronene： A Quantum-Chemical Characterization

The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett. 7 （2005） 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene.     

The argon spectrum in the range of 1200–2000 cm<Superscript>–1</Superscript>

Atomic argon spectrum in the range of 1200–2000 cm^–1 has been recorded by time-resolved Fourier transform spectroscopy. The lines have been identified using the oscillator strengths calculated by the quantum-defect method. Previously unknown energies of the 6h levels of Ar I have been found from the spectrum.     

相对论效应对类锂离子能级结构及辐射跃迁性质的影响

利用基于多组态Dirac-Hartree-Fock(MCDHF) 理论方法的相对论原子结构计算程序包GRASP2K, 细致计算了中性锂原子、类锂Be⁺, C³⁺, O⁵⁺, Ne⁷⁺, Ar¹⁵⁺, Fe²³⁺, Mo³⁹⁺, W⁷¹⁺及U^{89 +} 离子基组态及较低的激发组态1s²nl (n = 2---4, l =s,p,d,f) 的精细结构能级, 以及各能级间发生电偶极(E1) 自发辐射跃迁的能量、概率及振子强度. 同时, 在非相对论极限下, 计算了其相关原子参数. 通过对相对论及非相对论计算结果的比较, 系统研究了相对论效应对类锂等电子系列离子能级结构及E1跃迁性质的影响, 揭示了随原子核电荷数Z变化时, 跃迁能、振子强度强烈依赖于量子数n, l, j变化的规律; 同时, 目前的计算结果与其他已有的理论计算及实验测量结果进行了比较.     

Properties of a Si₂N molecule under an external electric field

In the present work,we adopt the ccsd/6-31g(d) method to optimize the ground state structure and calculate the vibrational frequency of the Si2N molecule.The calculated frequencies accord satisfactorily with the experimental values,which helps confirm the ground state structure of the molecule.In order to find how the external electric field affects the Si2N molecule,we use the density functional method B3P86/6-31g(d) to optimize the ground state structure and the time-dependent density functional theory TDDFT/6-31g(d) to study the absorption spectra,the excitation energies,the oscillator strengths,and the dipole moments of the Si2N molecule under different external electric fields.It is found that the absorption spectra,the excitation energies,the oscillator strengths,and the dipole moments of the Si2N molecule are affected by the external electric field.One of the valuable results is that the absorption spectra of the yellow and the blue-violet light of the Si2N molecule each have a red shift under the electric field.The luminescence mechanism in the visible light region of the Si2N molecule is also investigated and compared with the experimental data.     

Systematic multi-configuration Dirac-Fock calculations of the Kα and Kβ X-ray spectra of silicon ions

The transition energies, absorption oscillator strengths, line strengths and transition probabilities between computed levels are reported for the He-like to Ne-like Silicon ion sequences. Wavefunctions were determined relativistic configuration interaction (RCI) and multi-configuration Dirac-Fock (MCDF) technique included the Breit interaction, quantum electrodynamic (QED) corrections and nuclear mass corrections. The calculated values are in good agreement with the available experimental data and the recent theoretical values obtained from other methods. These data provide reference values for the level lifetimes, charge state distributions, and average charge of silicon plasmas.     

外电场下TCNQ的激发与光谱性质研究

采用密度泛函B3PLY方法优化了不同外电场下TCNQ分子的基态稳定构型、电偶极矩和分子的总能量，并且分析了TCNQ分子的HOMO-2到LUMO+2轨道的能量变化。然后利用杂化CIS-DFT方法在同样的基组下计算了外电场下TCNQ分子的前9个激发态的激发能、波长和振子强度，结果表明在没有外电场的情况下，TCNQ分子只有一个激发态能够激发，从基态跃迁到第1激发态。在有外电场的作用下，总能量随外电场的增加而逐渐减少，偶极矩随外电场的增加而不断增加。其前线轨道的能量也随外电场的增加不断减少，轨道分布也受外电场很大的影响。另外，外电场对TCNQ分子的激发波长也产生了一定影响。