Efficient recursive Gaussian integral calculation of anion photodetachment cross sections

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Photochemistry

Background:

• Photodetachment cross sections (PDCSs) are crucial for understanding anion dynamics.
• Calculating PDCSs theoretically relies heavily on transition moment integrals.
• Existing methods often face convergence challenges.

Purpose of the Study:

• To develop an efficient computational method for calculating transition moments.
• To accurately determine PDCSs for various atomic and molecular anions.
• To enable advanced studies in vacuum ultraviolet photochemistry.

Main Methods:

• Utilized plane wave approximation with analytical expressions for recursive Cartesian two-center Gaussian integrals.
• Incorporated random orientation of gas-phase molecular anions.
• Simplified integration for low anisotropy wavefunctions.

Main Results:

• Achieved excellent agreement with experimental and high-level theoretical results for numerous anions (e.g., H-, Li-, C-, O-, F-, OH-, CN-).
• Demonstrated superior computational efficiency for larger systems like benzyl and glycine anions.
• Successfully bypassed convergence issues inherent in traditional plane wave expansion.

Conclusions:

• The developed method provides an efficient and accurate way to calculate PDCSs.
• This technique has significant implications for the field of vacuum ultraviolet photochemistry.
• The method's efficiency makes it suitable for complex molecular systems.