Modeling L_2,3-edge X-ray absorption spectroscopy with linear response exact two-component relativistic time-dependent...

Area of Science:

• Computational Chemistry
• Spectroscopy
• Quantum Mechanics

Background:

• X-ray absorption spectroscopy (XAS) provides crucial element-specific chemical insights.
• Relativistic time-dependent density functional theory (TDDFT) has been used for L-edge XAS, but basis set and functional choices require further study.

Purpose of the Study:

• To implement and assess a generalized preconditioned locally harmonic residual algorithm for relativistic TDDFT.
• To comprehensively investigate basis set and density functional kernel effects on L-edge XAS modeling.
• To analyze L2,3-edge spectra of molecular complexes and compare with experimental data.

Main Methods:

• Implementation of a novel algorithm for complex-valued relativistic TDDFT.
• Application of relativistic linear response TDDFT with hybrid iterative diagonalization.
• Systematic error analysis focusing on energetics, intensities, and L2-L3 splitting.

Main Results:

• The developed method accurately models L-edge XAS, providing insights into energetics and intensities.
• Comparison with experimental data shows good agreement for L2,3-edge spectra.
• Evaluation of different theoretical methods and multideterminantal effects was performed.

Conclusions:

• The implemented relativistic TDDFT approach is a robust tool for L-edge XAS.
• This work establishes a foundation for more accurate theoretical predictions in XAS.
• The study highlights the importance of computational method selection for reliable spectral analysis.