Modeling L_2,3-Edge X-ray Absorption Spectroscopy with Real-Time Exact Two-Component Relativistic Time-Dependent...

Area of Science:

• Computational Chemistry
• Spectroscopy
• Quantum Mechanics

Background:

• X-ray absorption spectroscopy (XAS) is vital for understanding electronic and nuclear structure.
• Existing theoretical methods excel at modeling K-edge spectra but struggle with L-edge spectra.
• Accurate L-edge modeling requires advanced techniques, including spin-orbit coupling and noncollinear density functional theory.

Purpose of the Study:

• To develop and validate a computational method for accurately modeling X-ray absorption L-edge spectra.
• To investigate the performance of various basis sets and density functionals for L-edge spectral calculations.
• To demonstrate the method's applicability to both closed- and open-shell systems.

Main Methods:

• Utilized the real-time exact two-component method to incorporate one-electron spin-orbit coupling.
• Employed density functional theory (DFT) with noncollinear spin polarization.
• Calculated XAS spectra for SiCl4, TiCl4, CrO2Cl2, and [FeCl6]3-.

Main Results:

• Successfully modeled X-ray absorption L-edge spectra by including spin-orbit coupling.
• Evaluated the performance of different basis sets and density functionals for spectral accuracy.
• Demonstrated the recovery of individual molecular orbital transitions within the real-time framework.

Conclusions:

• The real-time exact two-component method offers a robust approach for L-edge XAS modeling.
• Accurate L-edge spectra prediction is achievable with appropriate theoretical treatments.
• This method enhances the capability of DFT for detailed electronic structure analysis.