arXiv subjects

Yizhi Qu

Publications and source records attributed to Yizhi Qu.

4 recordsLinked to original sources

arXiv2026

Plasma screening and configuration interaction effects induced large enhancement on L-shell photoionization cross sections and opacity

An opacity model that incorporates improved treatments of both plasma screening and configuration interaction (CI) effects is proposed, and a 25-30% enhancement on the iron L-shell opacity is predicted at solar interior temperatures. It is originated from the plasma screening induced 14-17% enhancement on the photoionization cross sections and the CI induced 10-20% enhancement on photoexcitation and photoionization cross sections for open L-shell ions. These explain the long-standing discrepancy between theoretical and experimental iron opacity [Nature 517, 56], and the relatively weaker enhancements on chromium and nickel opacity [Phys. Rev. Lett. 122, 235001] due to the sensitivity of these effects to the different L-shell electron population and plasma temperature/density. This letter provides the systematic interpretation of L-shell opacity measurements at solar interior temperatures, and advances the accurate simulation of opacity and radiative transport in high-energy-density plasma.

physics.atom-ph↗

arXiv2020

Statistical screening model for moderately coupled and dense plasmas

For atoms embedded in dense plasma, the plasma screening effects will greatly alter their structure and dynamics, and then determine the radiation transport properties of the plasma. In the present work, a new statistical model is proposed for treating electron screening effects on atoms in moderately/strongly coupled and dense plasmas, in which the three-body processes are found to significantly influence the plasma-electron density distributions and leads to a dependence of the distribution on the specific bound state of the targeted atom. As a critical check, the model is applied to simulate the emission spectra of He-like Aluminum and Chlorine in hot dense plasmas, and much better agreements of the line shifts are obtained with the experiments of Stillman et al. in 2017 and Beiersdorfer et al. in 2019 than previous calculation results. Compared with the classical molecular dynamic simulations of electron distributions in moderately coupled plasmas, the present model can better describe the low-energy electron distribution than other models and the multi-body effects are well considered. The present model provides a promising tool to reasonably treat the electron screening effect of non-equilibrium dense plasma on atoms with specific bound states, which is urgently needed in high-precision simulations of the atomic processes, plasma spectra and radiation transport properties etc.

physics.plasm-ph↗

arXiv2017

Hyperfine induced transitions probabilities from $4f^{14}5s5p~^3\mathrm{P}^o_{0,2}$ states in Sm-like ions

The hyperfine induced $4f^{14}5s5p~^3\mathrm{P}^o_{0,2}~-~4f^{14}5s^2~^1\mathrm{S}_0$ transition probabilities for highly charged Sm-like ions are calculated in the framework of the multi-configuration Dirac-Hartree-Fock method. Electron correlation, the Breit interaction and quantum electrodynamical (QED) effects are taken into account. For ions ranging from $Z=79$ to $Z=94$, $4f^{14}5s5p~^3\mathrm{P}^o_{0}$ is the first excited state, and the hyperfine induced transition is an dominant decay channel. For the $4f^{14}5s5p~^3\mathrm{P}^o_{2}$ state, the hyperfine induced transition (HIT) rates of Sm-like ions with $Z=82-94$ are reported as well as the magnetic dipole (M1) $^3\mathrm{P}^o_2 ~-~ ^3\mathrm{P}^o_1$, the electric quadrupole (E2) $^3\mathrm{P}^o_2 ~-~ ^3\mathrm{P}^o_{0,1}$, and the magnetic quadrupole (M2) $^3\mathrm{P}^o_2 ~-~ ^1\mathrm{S}_0$ transition probabilities. It is found that M1 transition from the $4f^{14}5s5p~^3\mathrm{P}^o_2$ state is the most important decay channel in this range on $Z \ge 82$.

physics.atom-ph↗

arXiv2015

Multi-configuration Dirac-Hartree-Fock calculations of excitation energies, oscillator strengths and hyperfine structure constants for low-lying levels of Sm I

The multi-configuration Dirac-Hartree-Fock method was employed to calculate the total and excitation energies, oscillator strengths and hyperfine structure constants for low-lying levels of Sm I. In the first-order perturbation approximation, we systematically analyzed correlation effects from each electrons and electron pairs. It was found that the core correlations are of importance for physical quantities concerned. Based on the analysis, the important configuration state wave functions were selected to constitute atomic state wave functions. By using this computational model, our excitation energies, oscillator strengths, and hyperfine structure constants are in better agreement with experimental values than earlier theoretical works.

physics.atom-ph↗