Multiplety

Official Resources

• Source Repository: https://github.com/gfabbris/multiplety
• License: Open source

Overview

Multiplety is a Python package for multiplet calculations of X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) spectra using the Cowan's atomic code and Racer programs. It provides a Jupyter notebook-based interface for setting up and running multiplet calculations for transition metal and rare-earth systems.

Scientific domain: Multiplet X-ray spectroscopy, atomic physics
Target user community: Researchers studying core-level spectra of correlated transition metal and rare-earth systems

Theoretical Methods

• Cowan's atomic code (Hartree-Fock with relativistic corrections)
• Racer code for transition matrices
• Crystal field theory
• Configuration interaction (CI)
• Spin-orbit coupling
• Slater-Condon parameter scaling
• Multiplet theory

Capabilities (CRITICAL)

• X-ray absorption spectroscopy (XAS) multiplet calculations
• RIXS multiplet calculations
• XAS dichroism (XMCD, XMLD)
• Temperature-dependent spectra
• Polarization-dependent spectra
• Interactive Jupyter notebook interface
• Automatic parameter setup from Cowan's code
• Custom crystal field splitting
• Slater-Condon parameter scaling

Sources: GitHub repository, Cowan's code documentation

Key Strengths

Cowan's Code Integration:

• Well-established atomic multiplet code
• Accurate radial integrals
• Relativistic corrections included
• Systematic parameter scaling
• Decades of validation

User-Friendly Interface:

• Jupyter notebook workflow
• Interactive parameter adjustment
• Visual output
• Step-by-step tutorials
• Python scripting

Spectroscopy Coverage:

• XAS with multiplet structure
• RIXS with full multiplet treatment
• Dichroism calculations
• Temperature effects
• Polarization dependence

Inputs & Outputs

• Input formats:

  • Python/Jupyter notebooks
  • Atomic configuration specifications
  • Crystal field parameters
  • Slater-Condon scaling factors

• Output data types:

  • XAS spectra
  • RIXS maps
  • Dichroism spectra
  • Energy level diagrams
  • Transition matrices

Interfaces & Ecosystem

• Cowan's code: Required external dependency
• Racer: Required for transition matrices
• Jupyter: Interactive interface
• Matplotlib: Visualization

Performance Characteristics

• Speed: Fast for single-atom multiplet calculations
• Accuracy: Good for atomic multiplet structure
• System size: Single atom/impurity models
• Memory: Low

Computational Cost

• XAS: Seconds to minutes
• RIXS: Minutes
• Typical: Very fast for atomic calculations

Limitations & Known Constraints

• Requires Cowan's code: External dependency needed
• Single atom: No ligand/cluster effects natively
• No DFT integration: Standalone multiplet only
• Installation: Cowan's code setup can be complex
• Documentation: Limited

Comparison with Other Codes

• vs Quanty: Multiplety uses Cowan's code, Quanty is Lua-based
• vs CTM4XAS: Multiplety is Python, CTM4XAS is MATLAB
• vs Crispy: Multiplety is standalone, Crispy wraps Quanty
• Unique strength: Direct Cowan's code integration, Python/Jupyter interface, simple setup

Application Areas

Transition Metal L-edges:

• 2p→3d XAS multiplet structure
• Crystal field splitting analysis
• Oxidation state determination
• Spin-state characterization

Rare-Earth M-edges:

• 3d→4f XAS multiplet structure
• Hund's rule coupling
• Crystal field effects
• Valence determination

RIXS of Correlated Systems:

• d-d excitations
• Charge transfer excitations
• Parametric studies
• Temperature dependence

Best Practices

Parameter Calibration:

• Scale Slater-Condon parameters (typically 70-85%)
• Validate against experimental spectra
• Use consistent scaling across edges
• Compare with charge transfer models

Crystal Field Setup:

• Use appropriate symmetry
• Start with DFT crystal field parameters
• Validate splitting patterns
• Consider low-symmetry distortions

Community and Support

• Open source on GitHub
• Limited but active development
• Jupyter notebook examples provided
• Based on well-established Cowan's code

Verification & Sources

Primary sources:

1. GitHub repository: https://github.com/gfabbris/multiplety
2. Cowan's code: R. D. Cowan, "The Theory of Atomic Structure and Spectra" (1981)

Confidence: VERIFIED

Verification status: ✅ VERIFIED

• Source code: ACCESSIBLE (GitHub)
• Documentation: Jupyter notebooks
• Active development: Maintained
• Specialized strength: Cowan's code integration for multiplet XAS/RIXS, Python/Jupyter interface