We report electronic properties of a hydrogen atom encaged by an endohedral cavity under the influence of a weak plasma interaction. We implement a finite-difference approach to solve the Schr€odinger equation for a hydrogen atom embedded in an endohedral cavity modeled by the Woods-Saxon potential with well depth V0, inner radius R0, thickness D, and smooth parameter g. The plasma interaction is described by a Debye-Huckel screening potential that characterizes the plasma in terms of a Debye screening length lD. The electronic properties of the endohedral hydrogen atom are reported for selected endohedral cavity well depths, V0, and screening lengths, lD, that emulate different confinement and plasma conditions. We find that for low screening lengths, the endohedral cavity potential dominates over the plasma interaction by confining the electron within the cavity. For large screening lengths, a competition between both interactions is observed. We assess and report the photo-ionization cross section, dipole polarizability, mean excitation energy, and electronic stopping cross section as function of lD and V0. We find a decrease of the Generalized Oscillator Strength (GOS) when the final excitation is to an s state as the plasma screening length decreases. For a final excitation into a p state, we find an increase in the GOS as the endohedral cavity well-depth increases. For the case of the electronic stopping cross section, we find that the plasma screening and endohedral cavity effects are larger in the low-to-intermediate projectile energies for all potential well depths considered. Our results agree well to available theoretical and experimental data and are a first step towards the understanding of dipole and generalized oscillator strength dependent properties of an atom in extreme conditions encaged by an endohedral cavity immersed in a plasma medium.

The spontaneous emission rate of two interacting excited atoms near a dielectric interface is studied using the photon closed-orbit theory and the dipole image method. The total emission rate of one atom during the emission process is calculated as a function of the distance between the atom and the interface. The results suggest that the spontaneous emission rate depends not only on the atomic-interface distances, but also on the orientation of the two atomic dipoles and the initial distance between the two atoms. The oscillation in the spontaneous emission rate is caused by the interference between the outgoing electromagnetic wave emitted from one atom and other waves arriving at this atom after traveling along various classical orbits. Each peak in the Fourier transformed spontaneous emission rate corresponds with one action of photon classical orbit.

By using the closed orbit theory, the photodetachment cross section of H- near a metal surface is derived and calculated. The results show that the metal surface has great influence on the photodetachment process. As the ion-surface distance is very large, the influence of the electrostatic image potential caused by the metal surface becomes small and can be neglected. The period, action, and length of the detached electron’s closed orbit are nearly the same as the case of the photodetachment of H- near an elastic interface. However, with the decrease of the ion-surface distance, the influence of the metal surface becomes significant. The amplitude of the oscillation in the photodetachment cross section becomes complicated. Each resonance peak in the Fourier transformed cross section is associated with one electron’s closed orbit. Unlike the case of the photodetachment of H- near an elastic interface, the length of the closed orbit does not equal the twice distance between the ion and the surface. But with the increase of the ion-surface distance, the length of the closed orbit approaches the case of the closed orbit near an elastic interface, which suggests the correctness of our method. This study provides a new understanding on the photodetachment process of H- in the presence of a metal surface.

The formulas of the quantum electrodynamics have been applied to calculate the spontaneous emission rate of excited atom in dielectric microcavity. The results exhibit damping oscillating patterns which depend sensitively on the scaling parameter and geometrical structure. Compared with the case that the emitting atom is immersed in dielectric, the spontaneous emission rate is depressed obviously and the center or the mean value of the oscillations is intimately related to the real refractive index of the local position where the atom is. In order to explain this phenomenon, we utilize the closed-orbit theory to deal with the classical trajectories of the emitted photon, and extract the corresponding frequencies of the oscillations by Fourier transform. It is found that the oscillations can be represented in terms of the closed-orbits of the photon motion constrained in dielectric microcavity, thus providing another perspective on the spontaneous emission of atom sandwiched by dielectric slabs.

The coupled equation method (CEM) has been applied to investigating the resonance structures for the ground state 1s2 2s 2S of the neutral lithium from the first threshold up to 64.5 eV. Resonance structures of atomic lithium due to single excitations of the 1s and 2s electrons are studied by infinite-order calculations in detail. The effect of spin-orbit splitting is also included for some of the low-lying 1s 2s np resonance, and the influence of the interference between 1s 2s 3S np and 1s 2s 1S np states on the resonance structure has been confirmed theoretically. The results show that the presented technique can give the reasonable resonance structures very well in photoionization processes.

Defect is built as that in the semiconductor when some metal posts are withdrawn regularly from the two-dimensional (2D) photonic crystal (PC) formed by triangular arrays of metal posts. Such defect can be used to design cavity. The relation among the lattice, the radius of post, the mode and frequency of this kind of cavity is researched in this paper. The design of this kind of cavity is introduced.

利用全实加关联方法得到的波函数计算类锂离子(Z=11～20)1s²3d-1s²nf(4≤n≤9)的偶极跃迁振子强度，三种规范下的计算结果符合的很好。将分立态的振子强度结果与单通道量子亏损理论相结合，计算在电离阚附近(|E|≤1／2)分立态间的束缚态-束缚态跃迁振子强度与束缚态-连续态跃迁的振子强度密度，实现了具有较大核电荷数的类锂离子量子跃迁特性的全能域理论预言。

采用全相对论量子力学GRASP2程序,选取三电子组态1s22s22p, 1s22s2p2, 1s22p3,有限核费米模型,Breit和QED的高阶微扰修正,系统地研究了类硼等电子序列磁偶极M1 1s22s22p*"2P3/2-2P1/2( Z=10～100)光谱跃迁的精细能级结构间隔,跃迁概率和振子强度,计算结果表明1s22s2 2p和1s22p3组态之间存在明显的非动力学组态相关,采用三电子组态计算的精细能级结构间隔较单电子组态的计算结果有了显著的改善.

采用相对论量子力学GRASP2程序,扩展平均能级EAL模型,有限核模型,考虑Breit和QED的高阶微扰修正,系统地研究了类硼等电子序列磁偶极M1 1s²2s²2p²P_{3/2—²P1/2(Z=10～100)光谱跃迁的精细能级结构间隔,跃迁概率和振子强度,所得结果和最近的实验数据及理论计算值进行了比较.计算结果表明:在ICF高温高密度激光等离子体中磁偶极矩M1跃迁几率过程不容被忽视.}

用多组态HXR自洽场方法和优化Slater径向积分方法相结合计算了类Be离子(Z=14-17,19,20)与软X射线激光研究有关的偶宇称组态2s3d、2s4d,2s5d和奇宇称组态2s3p,2s4f,2s5f的能级值以及这些能级之间的跃迁波长和振子强度。