Plasma-screening effects on positronium formation

Plasma-screening effects on positronium(Ps) formation for positron-hydrogen collisions in a Debye plasma environment is further investigated using the screening approximation model with the inclusion of the modified structure of Ps.More accurate Ps formation cross sections(n = 1, 2) are obtained for various Debye lengths from the Ps formation thresholds to 50 eV. The influence of considering modified bound-state wave functions and eigenenergies for the Ps is found to result in the reduction of the Ps formation cross sections at low energies, whereas it cannot counteract the enhancement of the Ps formation by the Debye screening.     

Coupled-Channels Optical Calculation for Electron Scattering from Metastable Helium

Coupled-channels optical calculations for total and resonance excitation integral cross sections for electron scattering on the metastable level 2^1,3S of helium are presented. The results are in agreement with other theoretical and experimental data.     

Triple-differential cross section for single ionization of H2 by electron impact

The triple-differential cross section (TDCS) for the (e,2e) ionization of a hydrogen molecule is calculated using the molecule distorted-wave Born approximation (MDWBA). Distorted waves are obtained by solving momentum-space coupled-channel Lippmann-Schwinger equations, including the ground state and the lowest-lying electronic state of b3Σu . TDCSs at the incident energy 100 eV in coplanar asymmetric geometry are reported. The present calculations are compared with the available experimental measurements and the theoretical results.     

Unnatural parity resonance states in positron-excited hydrogen scattering

<正>The coupled-channels optical method for positron scattering has been applied to investigate resonance states with unnatural parities in a positron-excited hydrogen system.The positronium formation channels and continuum channel are included via a complex equivalent local potential.Resonance states with angular momenta L = 1 to L = 2 and parities（—1）^L+1 are calculated.Resonance energies and widths are reported and compared with other theoretical calculations.We found that the opening positronium formation channels play an important role in forming nondipole Feshbach resonances.     

Differential cross sections for electron impact excitation of molecular hydrogen using the momentum-space multichannel optical method

In the present work, the momentum-space multichannel optical method is employed in four-state close-coupling calculations to study the electronic excitation of H_2 molecules by electron-impact. Particularly, differential cross sections for the X~1Σ_g~+→ b~3Σ_u~+, X~1Σ_g~+→ aΣ_g~+, and X~1Σ_g~+→ c~3Π_u transitions are reported. Comparison is made with the available experimental and theoretical results.     

Momentum-space calculation of electron-CO elastic collision

We report a momentum-space study on low-energy electron-CO collisions.Elastic differential cross sections(DCS) are obtained using a static-exchange-optical(SEO) model for the incident energies of 2,3,5,and 10 eV.Polarization effect of higher reaction channels,including the ionization continuum,on the elastic collision is represented by an ab initio equivalent-local optical potential.The cross sections are compared with experimental measurements and other theoretical results.     

建筑物周围绕流流场的三维数值模拟

运用κ-ε双方程湍流模型数值模拟了单个建筑物周围的空气流场,数值模拟结果与S.Muralami等人风洞实 验结果基本一致,在此基础上又模拟了一组建筑物群绕流的三维流场。