Two-particle coulomb Green function method with projected potential: application to He double photoionization.

Area of Science:

• Atomic Physics
• Quantum Mechanics
• Computational Chemistry

Background:

• Double photoionization (DIP) is a fundamental atomic process.
• Accurate theoretical calculations of DIP cross sections are computationally challenging.
• Existing methods often struggle with convergence and reproducing experimental angular distributions.

Purpose of the Study:

• To develop and validate a new computational method for fully differential double photoionization (FDIP) cross sections.
• To apply the method to two-electron systems, specifically helium.
• To assess the method's accuracy and convergence properties.

Main Methods:

• Exploitation of the Green function for two noninteracting electrons.
• Projection of the residual potential onto L(2)-basis functions.
• Calculation of FDIP cross sections in both acceleration and velocity gauges.

Main Results:

• The new method successfully computes FDIP cross sections for helium.
• Calculations show convergence in absolute values between acceleration and velocity gauges.
• The method reproduces measured angular distributions with tunable accuracy at 100 eV excess energy.

Conclusions:

• The developed Green function-based method is effective for calculating FDIP cross sections in two-electron systems.
• The approach demonstrates good agreement with experimental data.
• The method shows potential for generalization to many-electron atoms.