Differential equation for the ground-state density of a model spin-compensated atom in an external potential

The study of Gál and March (2009) [1] is utilized to derive a third-order differential equation for the ground-state electron density of two-electron model atoms having inverse-square repulsion, but arbitrary external potential. The result offers hope of progress on He-like atomic ions.     

Precision spectroscopy of the helium atom

Persistent efforts in both theory and experiment have yielded increasingly precise understanding of the helium atom. Because of its simplicity, the helium atom has long been a testing ground for relativistic and quantum electrodynamic effects in few-body atomic systems theoretically and experimentally. Comparison between theory and experiment of the helium spectroscopy in 1s2p³P _J can potentially extract a very precise value of the fine structure constant á. The helium atom can also be used to explore exotic nuclear structures. In this paper, we provide a brief review of the recent advances in precision calculations and measurements of the helium atom.      

氦原子能级的变分微扰计算

用变分微扰论计算了氦原子1S2S态两个能级的能量.先用单参数变分法计算,再进行二级微扰计算,改进了纯微扰论的结果,得到的能量值与实验数据较好相符.     

动量表象中氦原子微扰论的计算

根据微扰论,在动量表象中讨论了三维和二维氦原子两电子体系基态能级一级修正的表达式.对于推广的两电子二体作用势,给出了基态能级一级修正的值.     

氩原子和类氩离子相对论修正

以相对论修正哈密顿(包括质量修正、单体和双体达尔文修正、自旋-自旋接触相互作用)的球张量形式为基础, 借助不可约张量理论导出了类氩体系基态能量的相对论修正的解析表达式. 在斯莱特表象中完成了所有的角向积分和自旋求和计算, 能量的相对论修正式用径向矩阵元的线性组合来表示.对类氩体系基态能量的相对论修正值进行了具体计算,相对误差均小于0.0459%     

氦制冷系统透平膨胀机的测试

为满足中国散裂中子源(CSNS)工程预期发展及未来工程升级需要,建立了一套氦制冷系统。该制冷系统采用氦透平膨胀机,通过气体绝热膨胀来获得低温。文中介绍了透平膨胀机的设计参数、启动条件和运行情况,并对透平膨胀机运行性能进行了分析。实验表明,氦透平膨胀机的设计满足了CSNC装置对冷量的需求,透平效率高于设计值。     

氦原子2 3P态自旋-其他轨道相互作用的理论计算

借助不可约张量理论,导出了氦原子2^3P态自旋-其他轨道相互作用能的理论计算式,在推导过程中完成了所有角向积分和自旋求和计算．     

电子相关和相对论对M_2Te(M=Cu,Ag,Au)的几何结构和稳定性的修正

使用相对论的和非相对论的赝势在HF ,MP2 ,CCSD和CCSD(T)水平上计算了M2 Te(M =Cu ,Ag ,Au)的平衡几何和振动频率。计算的结果表明 ,这些化合物的基态 (单态 ) ,弯曲结构是稳定的 ,线性结构是不稳定的。在MP2水平上研究了电子相关对这些化合物的几何结构的修正。电子相关对键角的修正是非常明显的 ,对于M =Cu ,Ag ,Au ,角∠M Te M分别减少了 2 3.3°,2 1.8°和 2 1.8°。电子相关对键长的修正是微小的。相对论效应轻微地缩短了Au2 Te的键长。比较这三个化合物 ,Au2 Te相对稳定。     

EAST低温系统已研制氦透平膨胀机测试分析

EAST氦低温系统是EAST( Experimental Advanced Super-conducting Tokamak)先进超导托卡马克实验装置重要子系统之一;4 台氦透平膨胀机又是EAST氦低温系统的核心部件.文中主要对已研制出的1台氦透平膨胀机的结构、调试过程与调试结果等进行一些分析,还给出了氦透平的启动过程...     

Accurate calculations of the helium atom in magnetic fields

The 1 1 0 +,1 1 (-1) + and 1 1 (-2) + states of the helium atom in the magnetic field regime between 0 and 100 a.u.are studied using a full configuration-interaction (CI) approach.The total energies,derivatives of the total energy with respect to the magnetic field and ionisation energies are calculated with Hylleraas-like functions in spherical coordinates in low to intermediate fields and Hylleraas-Gaussian functions in cylindrical coordinates in intermediate to high fields,respectively.In intermediate fields,the total energies and ionisation energies are determined in terms of Hermite interpolation,based on the results obtained with the two above-mentioned basis functions.Calculations show that the current method can produce lower total energies and larger ionisation energies,and make the two ionisation energy curves obtained with the two above-mentioned basis functions join smoothly in intermediate fields.Comparisons are also made with previous works.     

氦原子高激发态的塞曼效应

利用塞曼哈密顿的球张量形式以及塞曼哈密顿在耦合表象中的矩阵元公式,在考虑磁场二次项作用的基础上,研究了氦原子n3P(n=4,5)高激发态的塞曼效应,给出解析解,并绘出了塞曼能级分裂图.     

Relativistic correction for the Zeeman effect in a hydrogen-like atom

Based on an algebraic system of equations whose eigenvalues in the semirelativistic approximation determine the magnetic splitting of energy levels of two coupled Dirac particles with charges ±e and different masses, the splitting in extremely weak and weak magnetic fields is determined. In addition, a system of equations for charged particles with anomalous magnetic moments is given. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–13, December, 2006.     

Dispersion relations for the Zeeman effect in the hydrogen atom

An analysis of the analyticity properties of the quadratic Zeeman energy shifts in the hydrogen atom leads us to once-subtracted dispersion relations for the energy levels. These relations (i) provide a compact representation of the general properties of the energy shifts, (ii) allow us to calculate energy levels for a wide range of values of the field.     

The antiprotonic helium atom

The Born-Oppenheimer approximation is used to discuss the high rotational and vibrational state of the (He p⁻)e⁻ system in the electronic 1sσ and 2pσ states. Very high angular momentum states, in which the antiproton is well outside the electron orbit, have a Rydberg-like character. states in which the antiproton is within the 1sσ electron orbit have enhanced radiative lifetimes due to the polarization of the 1sσ state by the antiproton. This effect may account for the long-lived component observed in antiproton destruction in He. Preliminary results on the effect of coupling to the 2pσ well, in which the polarization effects enhance the decay rate, are also presented. Some consequences for the suggestion that metastable antiprotonic He atoms may be used to promote antihydrogen formation are discussed.     

氦原子基态的斯塔克效应

用微扰与变分相结合的方法计算了氦原子基态的斯塔克效应,通过计算发现这种方法简便直观,尤其适用于低激发态且电子数不太多的原子．     

Metastable (2S) helium atom scattering from NiO(100) and Cu(100) surfaces

The scattering of metastable 2³S He atoms (He*) from cleaved NiO(100) as well as from clean and CO-covered Cu(100) surfaces has been studied. For these varied surfaces, which were characterized in situ by ground state He atom scattering, only broad He* angular distributions without any diffraction peaks were observed. For metastable He atoms scattered from the clean Cu(100) surface a total survival probability of 1×10⁻⁶ was determined. For NiO(100) and the CO-covered Cu(100) surface values of about 1×10⁻⁵ were obtained. Time-of-flight spectra of the surviving He* atoms revealed a substantial energetic broadening which increases with the substrate temperature. This behaviour indicates a large well depth for the He*–surface interaction potential and is discussed in terms of an enhanced multiphonon excitation and/or trapping probability upon the scattering.     

Spectroscopy of molecules in helium droplets

The work reviewed in the talk explores the possibilities of using molecules immersed in liquid helium as probes to study superfluidity on the microscopic level. For this purpose liquid ⁴He, ³He and mixed ⁴He/³He droplets consisting of 10³–10⁵ atoms have been doped with single molecules or a small defined number of molecules which form clusters in the droplet interior. The dopants were investigated with high-resolution optical spectroscopy. The electronic and rovibrational spectra show unusually sharp spectral lines and unexpected features such as a distinct gap between the zero phonon line and the phonon wing as well as the free rotations of single molecules. Both are not observed in colder nonsuperfluid ³He droplets and therefore are considered to be new microscopic manifestations of superfluidity. Spectroscopic studies of small p-H₂ and o-D₂ clusters surrounding a single chromophore molecule formed in the interior of the He droplets are also reported.     

汞原子塞曼效应分裂谱线相对强度的测量

为了研究塞曼效应分裂谱线的相对强度,分析了Hg(546.1 nm)谱线能级在外磁场中的分裂情况,详细给出了分裂能级的量子数分布和理论相对强度;在此基础上采用CCD拍摄了分裂谱线干涉圆环的图像,并对其进行了强度分析,通过图像强度处理得到各分裂谱线相对强度与理论分析结果十分接近;表明采用CCD图像技术能较好的分析塞曼效应现象和规律.