PhotoionizationGTO.jl

Official Resources

• Repository: https://github.com/antoine-levitt/PhotoionizationGTO.jl
• License: MIT (implied by Julia ecosystem norms, check repo)
• Documentation: GitHub README

Overview

PhotoionizationGTO.jl is a specialized Julia package for calculating photoionization spectra using Time-Dependent Density Functional Theory (TDDFT). It uniquely employs Gaussian-type orbitals (GTOs) to describe the bound states while handling the continuum states appropriate for photoionization processes, interfacing with the PySCF library for integrals.

Scientific domain: Molecular photoionization, chemical physics Target user community: Julia developers, quantum chemists studying photo-ejection

Theoretical Methods

• Linear-Response TDDFT: Frequency-domain response formalism
• Gaussian Basis Sets: Use of GTOs for efficient molecular description
• Stieltjes Imaging / Complex Basis: Techniques for extracting continuum information from L^2 basis sets (check specific implementation details in source)
• Dyson Orbitals: Calculation of Dyson orbitals for ionization amplitudes

Capabilities

• Photoionization Cross-Sections: Calculation of energy-dependent cross-sections
• Dyson Orbitals: Analysis of the ionized electron channel
• Julia-Python Hybrid: Leverages Julia's speed and PySCF's robust integrals
• Reproducibility: Explicit dependency management via Manifest.toml

Inputs & Outputs

• Input formats: Julia scripts (.jl), integrating PySCF molecule definitions
• Output data types:
  • Cross-section data arrays
  • Dyson orbital coefficients
  • Spectral plots (via Julia plotting libraries)

Interfaces & Ecosystem

• PySCF: Critical dependency for ground state SCF and integrals (via PyCall)
• Julia Ecosystem: Integration with standard Julia linear algebra and plotting tools

Performance Characteristics

• Efficiency: Julia provides near-C performance for the custom TDDFT logic.
• Bottlenecks: Integral evaluation depends on PySCF (C/Python) performance.

Usage & Best Practices

• Installation: Use Julia's Pkg mode: ] dev https://github.com/antoine-levitt/PhotoionizationGTO.jl
• Workflow: Define molecule in PySCF, pass to PhotoionizationGTO, run spectral calculation.

Limitations & Known Constraints

• Documentation: Limited to README; requires reading source code for advanced features.
• Maturity: Research code, may lack convenience features of established packages.

Citations

• Primary: Cite the repository and A. Levitt et al. publications related to the method.