Jiang Gang

Ground-State Ionization Potentials for Lithium through Neon Isoelectronic Sequences with Z = 37–82

The ground-state ionization potentials of different isoelectronic sequences are calculated systemically with the multi-configuration Dirac–Fock method. The relativistic corrections, Breit and QED effects are included in the calculation. These results are compared with the scanty existing theoretical and experimental data in the literature, Analytical expressions are obtained for expressing our theoretical data along the different sequences.

Elastic properties and electronic structures of lanthanide hexaborides

The structural, elastic, and electronic properties of a series of lanthanide hexaborides (LnB6) have been investigated by performing ab initio calculations based on the density functional theory using the Vienna ab initio simulation package. The calculated lattice and elastic constants of LnB6 are in good agreement with the available experimental data and other theoretical results. The polycrystalline Youngs modulus, shear modulus, the ratio of bulk to shear modulus B/G, Poissons ratios, Zener anisotropy factors, as well as the Debye temperature are calculated, and all of the properties display some regularity with increasing atomic number of lanthanide atoms, whereas anomalies are observed for EuB6 and YbB6. In addition, detailed electronic structure calculations are carried out to shed light on the peculiar elastic properties of LnB6. The total density of states demonstrates the existence of a pseudogap and indicates lower structure stability of EuB6 and YbB6 compared with others.

Intercombination transitions of the carbon-like isoelectronic sequence

Energy levels, wavelengths, transition rates, oscillator strengths, and lifetimes between the 2s22p2 3P1, 2s22p2 3P2, and 2s2p3 5S2 levels of ions in the carbon-like (C-like) isoelectronic sequence (nuclear charges Z = 7–92) are calculated in the valence and core-valence limits using the multiconfiguration Dirac—Fock method. The Breit interaction, quantum electrodynamics (QED), and finite nuclear mass effects are taken into account in subsequent relativistic configuration-interaction calculations. The calculated energies and transition rates are compared with the critically evaluated experimental values and other recent calculated results. Our calculated data are in good agreement with these data.

Geometrical structures, vibrational frequencies, force constants and dissociation energies of isotopic water molecules （H2O, HDO, D2O, HTO, DTO, and T2O） under dipole electric field

The dissociation limits of isotopic water molecules are derived for the ground state. The equilibrium geometries, the vibrational frequencies, the force constants and the dissociation energies for the ground states of all isotopic water molecules under the dipole electric fields from ?0.05 a.u. to 0.05 a.u. are calculated using B3P86/6-311++G(3df,3pf). The results show that when the dipole electric fields change from ?0.05 a.u. to 0.05 a.u., the bond length of H?O increases whereas the bond angle of H?O?H decreases because of the charge transfer induced by the applied dipole electric field. The vibrational frequencies and the force constants of isotopic water molecules change under the influence of the strong external torque. The dissociation energies increase when the dipole electric fields change from ?0.05 a.u. to 0.05 a.u. and the increased dissociation energies are in the order of H2O, HDO, HTO, D2O, DTO, and T2O under the same external electric fields.

Enhancement of the Number of Fast Electrons Generated in a Laser Inverse Cone Interaction

Enhancement of the energy-conversion efficiency from laser to target electrons is demonstrated by two-dimensional particle-in-cell simulations in a laser-inverse cone interaction. When an intense short-pulse laser illuminates the inverse cone target, the electrons at the cone end are accelerated by the ponderomotive force. Then these electrons are guided and confined to transport along the inverse cone walls by the induced electromagnetic fields. A device consisting of inverse hollow-cone and multihole array plasma is proposed in order to increase the energy-conversion efficiency from laser to electrons. Particle-in-cell simulations present that the multiholes transpiercing the cone end help to enhance the number of fast electrons and the maximum electron energy significantly.

Systematical Study on Ground-State Ionization Potentials for Boron and Carbon Isoelectronic Sequences with Z = 6–42

The multi-configuration Dirac-Fock method is used in this work to calculate ground-state ionization potentials of Boron and Carbon isoelectronic sequences from Z = 6 to Z = 42. And the contribution of relativistic corrections, nuclear volume effect, Breit and QED effects to the results is discussed in the calculation. The results are compared with the scanty existing theoretical and experimental data in the literature and good agreements are achieved. Then analytical expressions of Ionization potential along Boron and Carbon isoelectronic sequences are obtained.

Spectrum Simulation of Li-Like Aluminium Plasma

X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al9+ and Al11+) charge states of the target ion (Al10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes.

Relative Distribution of Au48+ ～ Au52+ in Au Plasma by Ionization Dynamics

The present work proposes a theoretical method called ionization dynamics to derive the ionic charge state distribution. Using relativistic quantum mechanics to calculate the energy level lifetime and average ionic lifetime of each ion, the first-order ionization rate constant can be obtained. Based on these data, from the solution of differential equations for consecutive-irreversible ionization reactions, one will be able to derive the ionic charge state distribution. The calculated average positive charge 49.24 of Au48+ ~ Au52+ and their relative distribution are in good agreement with the results of Lawrence Livermore National Laboratory.

Electron impact excitation of Ni-like gold studied by Dirac R-matrix method

We calculate the electron impact excitation of Ni-like gold by using the Dirac R-matrix theory, and the corresponding collision strengths and effective collision strengths are obtained. In the calculations of the level energy, (1s22s22p6)3s23p63d10, 3s23p63d94l, 3s23p53d104l, and 3s3p63d104l (l = 0, 1, 2, 3) configurations are included and 107 fine-structure levels are generated. In the calculations of the collision strengths, only the first 59 levels are included. Comparisons are made with the distorted wave (DW) results of Zeng et al. for both collision strengths and effective collision strengths. For the collision strengths, the two sets of calculations are in excellent agreement for most of the transitions. However, because of the inclusion of the resonances, our effective collision strengths are generally several times larger than those of Zeng et al.. The accuracy of our calculations is assessed.

Effects of Laser Parameters on Fast Electron Generation in a Multihole Array Target

The effects of laser parameters on the production of fast electrons from laser-multihole array target interaction are investigated theoretically via two-dimensional particle-in-cell simulations. The results show that the fast electron temperature is scaled by I1/2?2 with I and ? being the laser intensity and wavelength. When the laser intensity reaches 2.14 ? 1020 W?cm?2, a typical bi-Maxwellian energy distribution is observed. The slope temperature of the low-energy component fits the linear scaling Th ~ I1/2 well. The high-energy component has an increased slope temperature comparable to ponderomotive potential scaling law. In addition, the electron temperature rises linearly with the pulse duration, Th ~ ?t. The divergence angle of the fast electrons increases with laser intensity and pulse duration, but is independent of laser wavelength.