Correlation function quantum Monte Carlo calculations for ground and excited states of many-electron atoms and ions in neutron-star magnetic fields

本项目的目标是将关联函数量子蒙特卡罗(CF)方法应用于计算中子星磁场中重原子和离子的原子数据。该方法允许计算基态、激发态和跃迁几率，已被Jones、Ortiz和Ceperley成功地应用于弱中子星磁场中原子数据的计算。他们使用了球对称的Hartree-Fock基组，这限制了他们可以研究的最大场强。这些作者已经指出，使用绝热近似可以为强磁场选择不同的基组。这正是我们想要做的：选择能够解释随着磁场的增加而逐渐占据主导地位的柱状对称性的基集，并将它们合并到CF算法中。这些基态将由我们在之前DFG资助的项目中发展的一种方法来计算，即Hartree-Fock-Roothaan基态，其中包含来自更高Landau能级的混合物，甚至超过绝热近似。该项目的重要性是双重的：在方法论方面，我们将测试和演示CF方法的范围和力量。在物理方面，我们将以前所未有的精度为中子星磁场中的中重原子和离子生成波长和振子强度的原子数据，这些数据与最近在孤立中子星的热发射光谱中发现的特征的分析直接相关。

The goal of this project is to apply the correlation function quantum Monte Carlo (CF) method to the calculation of atomic data of medium-heavy atoms and ions in neutron star magnetic fields. The method, which allows for the calculation of both ground and excited states, and transition rates, has been successfully applied by Jones, Ortiz and Ceperley to the calculation of atomic data in weak neutron star magnetic fields. They used Hartree-Fock basis sets with spherical symmetry, which limited the maximum field strength they could study. These authors already remarked that a different basis set could be chosen for strong magnetic fields using the adiabatic approximation . This is exactly what we want to do: Take basis sets which account for the growing dominance of the cylindrical symmetry as the magnetic field is increased and to incorporate them into the CF algorithm. These basis states will be computed by a method that has been developed by us in a previously DFG funded project, namely, Hartree-Fock-Roothaan basis states, with admixtures from higher Landau levels, which even go beyond the adiabatic approximation. The importance of the project is twofold: On the methodological side we will test and demonstrate the scope and power of the CF method. On the physical side we will generate atomic data for wavelengths and oscillator strengths with unprecedented accuracy for medium-heavy atoms and ions in neutron star magnetic fields that are of immediate relevance to the analysis of features recently discovered in the thermal emission spectra of isolated neutron stars.