Theoretical study on non-sequential double ionization of carbon disulfide with different bond lengths in linearly polarizedlaser fields

By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization(DI) process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ionization probability presents a "knee" structure with equilibrium internuclear distance R = 2.9245 a.u.(a.u. is short for atomic unit). As the bond length of CS increases, the DI probability is enhanced and the "knee" structure becomes less obvious. In addition,the momentum distribution of double ionized electrons is also investigated, which shows the momentum mostly distributed in the first and third quadrants with equilibrium internuclear distance R = 2.9245 a.u. As the bond length of CS increases,the electron momentum becomes evenly distributed in the four quadrants. Furthermore, the energy distributions and the corresponding trajectories of the double-ionized electrons versus time are also demonstrated, which show that the bond length of CS in the CS_2 molecule plays a key role in the DI process.     

The Scaling Law in the Fine-Structure Splitting of ls2np States for the Lithium Isoelectronic Sequence

The ＇full-core plus correlation＇ （FCPC） and the ＇minimizing the expectation value of the Hamiltonian＇ methods are extended to calculate the fine-structure splitting of ls2np （n = 2-9） states for the lithium-like systems from Z = 21 to 30. The leading order relativistic effect is included by using first-order perturbation theory. The higher- order relativistic and the quantum-electrodynamics contributions to the fine-structure splitting are investigated under a hydrogenic approximation with effective nuclear charges, Our results are compared with other theoretical calculations and experimental results. It is shown that the FCPC method is also effective to obtain the ionic structure for high nuclear ions of lithium-like systems. By fitting our theoretical results, the scaling law of the fine-structure splitting of the lithium isoelectronie sequence behaves like a quartie function of the screened nuclear charge Z＊.     

类锂离子（Z = 21~30）1s22s和1s22p态近核处电子密度的下限

应用行列式条件和电子-原子核尖点(cusp)条件计算了核电荷数Z=21-30的类锂离子1s22s和1s22p态近核处电子密度的理论下限.该下限由Angulo和 Dehesa等人推导(见Phys. Rev. A 42 641 (1990)）的包含两个或者更多径向期待值的不等式给出. 结果表明,该下限对于高核电荷离子也同样适用,而且其品质要好于以前所知道的;计算中所用的波函数在这些具有较高核电荷离子体系的整个组态空间中都是准确可靠的.     

Double ionization of helium interacting with elliptically polarized laser pulse by classical ensemble simulations

This paper uses the classical ensemble method to study the double ionization of a 2-dimensional (2D) model helium atom interacting with an elliptically polarized laser pulse. The classical ensemble calculation demonstrates that the ratio of double to single ionization decreases with the increasing ellipticity of the driving field. The classical scenario shows that there are hardly any e--e recollisions with the circularly polarized laser pulse. The double ionization probability is studied for linearly and circularly polarized laser pulses. The classical numerical results are consistent with the semiclassical rescattering mechanism and in agreement with the experimental results and the quantum calculations qualitatively.     

类锂离子(Z=21～30)1s~22s和1s~22p态近核处电子密度的下限(英文)

应用行列式条件和电子-原子核尖点(cusp)条件计算了核电荷数Z=21～30的类锂离子1s~22s和1s~2p态近核处电子密度的理论下限.该下限由Angulo和Dehesa等人推导(见Phys.Rev.A 42 641(1990))的包含两个或者更多径向期待值的不等式给出.结果表明,该下限对于高核电荷离子也同样适用,而且其品质要好于以前所知道的;计算中所用的波函数在这些具有较高核电荷离子体系的整个组态空间中都是准确可靠的.     

原子核体积效应对类锂离子体系基态能量的修正

用全实加关联的方法得到类锂离子15~22s(Z=21～30)波函数,给出了原子核体积效应公式,计算了原子核的体积效应及质量效应对类锂离子能级的修正.结果显示。在中等大小的核电核情形,原子核体积效应对类锂离子能级的修正要比质量效应对类锂离子能级的修正要显著;随着核电核数的增加,原子核体积效应越来越重要.     

Tune-out wavelengths for the alkaline-metal atoms

An approximation formula is developed to determine the tune-out wavelengths for the ground states of the alkalinemetal atoms lithium,sodium and cesium from the existing relativistic reduced matrix elements and experimental energies.The first longest tune-out wavelengths for Li,Na,and Cs are 670.971 nm,589.557 nm,and 880.237 nm,respectively.This is in good agreement with the previous high precise results of 670.971626 nm,589.5565 nm,and 880.25 nm from the relativistic all-order many-body perturbation theory(RMBPT) calculation[Phys.Rev.A 84 043401(2011)].     

Charge density at the nucleus and radial behavior of ground state for lithium-like ions with Z = 21 to 30

By using the full-core plus correlation (FCPC) type wave functions, the accurate charge densities ρ(0) at the nucleus and the radial expectation values of the ground states for the lithium-like systems with Z = 21 to 30 are obtained. The determinantal conditions and the electron-nucleus cusp condition are used to calculate the inequalities of the upper and the lower bounds to ρ(0) with two or more expectation values. These inequalities, derived by Angulo and Dehesa [Phys. Rev. A 44 1516 (1991)], are verified to be also valid for these ions with higher nuclear charge. The present results show that the wave functions used in this paper are satisfactory in the whole configuration space for these ions with higher nuclear charge.