Computing photoionization spectra in Gaussian basis sets.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Spectroscopy

Background:

• Accurate computation of photoionization spectra is crucial for understanding atomic and molecular electronic structures.
• Traditional methods often require complex approximations or extensive computational resources.

Purpose of the Study:

• To present a novel, efficient, and accurate method for computing photoionization spectra.
• To enable reliable spectral calculations using standard computational chemistry tools.

Main Methods:

• Linear-response, time-dependent density functional theory (LR-TDDFT).
• Expansion of electronic orbital variations using delocalized functions derived from the Helmholtz equation.
• Green's function-based approach.

Main Results:

• The method successfully reproduces photoionization spectra without artificial regularization or localization.
• Accurate spectra were obtained for semilocal exchange-correlation functionals.
• The approach is effective even with relatively small, standard Gaussian basis sets.

Conclusions:

• The Green's function-based LR-TDDFT method provides a robust and accurate way to compute photoionization spectra.
• This technique simplifies spectral calculations, making them more accessible for atoms and molecules.
• The findings pave the way for more efficient theoretical investigations in quantum chemistry.