具有天体物理学重要性的中性硫过渡数据的理论研究
Theoretical investigation of transition data of astrophysical importance in neutral sulphur
AI总结：
本研究通过MCDHF和RCI方法计算中性硫的原子数据，提升跃迁率精度，为天体物理学提供更可靠的原子数据支持。
摘要：
准确且全面的原子数据对于恒星光谱建模至关重要。特定线的振子强度的不确定性会直接转化为所推导的元素丰度的不确定性；不完整或有偏的原子数据集会对非局部热力学平衡（non-LTE）建模产生显著误差。因此，理论计算原子数据对于补充有限的实验结果至关重要。在本工作中，我们提供了大量原子数据，包括1730个电偶极（E1）跃迁的振子强度、跃迁率和寿命，这些跃迁涉及中性硫（S I）中107个能级的跃迁，使用多配置Dirac-Hartree-Fock（MCDHF）和相对论性配置相互作用（RCI）方法计算。这些能级属于以下配置：$\mathrm{3p^3np (n=3-7)}$，$\mathrm{3p^3nf (n=4,5)}$，$\mathrm{3s3p^5}$，$\mathrm{3p^3ns (n=4-7)}$，和$\mathrm{3p^3nd (n=3-6)}$。通过比较Babushkin和Coulomb规范之间的跃迁率差异，并结合消去因子（CF）分析，评估了计算跃迁率的准确性。大约16%的从头计算结果获得了A-B精度分类，对应于不确定性在10%以内的范围，如美国国家标准与技术研究院（NIST ASD）原子光谱数据库所定义。应用精细调谐技术发现，显著提高了Coulomb规范下的结果精度，从而提高了Babushkin和Coulomb规范之间的一致性；约24%的精细调谐跃迁数据被分配到A-B精度类别。
英文摘要：
Accurate and comprehensive atomic data are essential for the modelling of stellar spectra. Uncertainties in the oscillator strengths of specific lines used for abundance analyses directly translate into uncertainties in the derived elemental abundances; incomplete or biased atomic data sets can impart significant errors in non-local thermodynamic equilibrium (non-LTE) modelling. Theoretical calculations of atomic data are therefore crucial to supplement the limited experimental results. In this work, we present extensive atomic data, including oscillator strengths, transition rates, and lifetimes for 1730 electric-dipole (E1) transitions among 107 levels in neutral sulphur (S I) using the multi-configuration Dirac-Hartree-Fock (MCDHF) and relativistic-configuration-interaction (RCI) methods. These levels belong to the configurations $\mathrm{3p^3np (n=3-7)}$, $\mathrm{3p^3nf (n=4,5)}$, $\mathrm{3s3p^5}$, $\mathrm{3p^3ns (n=4-7)}$, and $\mathrm{3p^3nd (n=3-6)}$. The accuracy of the computed transition rates is assessed by combining the comparison of the differences in transition rates between the Babushkin and Coulomb gauges with a cancellation-factor (CF) analysis. Approximately 16% of the ab initio results achieved an accuracy classification of A-B, corresponding to uncertainties within 10%, as defined by the Atomic Spectra Database of the National Institute of Standards and Technology (NIST ASD). Applying a fine-tuning technique was found to significantly improve the accuracy of the results in the Coulomb gauge, thereby improving the consistency between the Babushkin and Coulomb gauges; about 24% of the fine-tuned transition data are assigned to the accuracy classes A-B.
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