Density functional theory for molecular multiphoton ionization in the perturbative regime

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Physics

Background:

• Molecular multiphoton ionization is crucial for understanding molecular responses to intense light.
• Accurate theoretical calculations are needed to interpret experimental results and predict molecular behavior.

Purpose of the Study:

• To develop a general computational method for calculating molecular multiphoton ionization cross sections.
• To apply the method to small and medium-sized molecules, demonstrating its efficiency and accuracy.

Main Methods:

• Implementation of lowest nonvanishing order perturbation theory within density functional theory.
• Expansion of wave functions in a multicentric basis set, utilizing molecular point group symmetry.
• Calculation of ionization cross sections and angular asymmetry parameters for various ionization orders and light polarizations.

Main Results:

• The proposed method successfully calculates multiphoton ionization cross sections and angular asymmetry parameters for H(2)(+) and benzene.
• The formalism is applicable to medium-sized molecules, showcasing its generalizability.
• Calculations considered both fixed and random molecular orientations and different light polarizations.

Conclusions:

• The developed methodology provides an efficient and accurate way to compute molecular multiphoton ionization.
• This approach can be applied to a wider range of molecules, advancing the study of molecular photoionization processes.