StoBe

Official Resources

• Homepage: https://www.fz-juelich.de/pgi/pgi-1/DE/Home/home_node.html
• Documentation: Included with distribution
• Source Repository: Available upon request from developers
• License: Free for academic use

Overview

StoBe (Stockholm-Berlin) is a DFT code based on Gaussian-type orbitals (GTO) specifically designed for the simulation of core-level X-ray spectroscopy including XAS, XES, and XPS. It uses the transition potential (TP) method and half/core-hole approaches for accurate core excitation and emission calculations.

Scientific domain: X-ray absorption, emission, and photoelectron spectroscopy of molecules and clusters
Target user community: Researchers studying molecular and cluster core-level spectroscopy with DFT

Theoretical Methods

• Density Functional Theory (DFT)
• Gaussian-type orbital (GTO) basis sets
• Transition potential (TP) method for XAS
• Half core-hole (Z+1/2) approximation
• Full core-hole (Z+1) approximation
• Linear response TDDFT for core excitations
• Static exchange (STEX) method
• LDA, GGA, hybrid functionals
• Scalar relativistic corrections (ZORA)
• Basis set superposition error (BSSE) correction

Capabilities (CRITICAL)

• X-ray absorption spectroscopy (XAS/NEXAFS)
• X-ray emission spectroscopy (XES)
• X-ray photoelectron spectroscopy (XPS)
• Core-level binding energies
• Transition potential calculations
• STEX calculations
• Cluster and molecular calculations
• Symmetry-adapted calculations
• Geometry optimization
• Vibrational analysis
• Charged and neutral excitations

Sources: StoBe documentation, J. Chem. Phys. 117, 963 (2002)

Key Strengths

Transition Potential Method:

• Accurate core excitation energies
• Beyond sudden approximation
• Includes relaxation effects
• Systematic improvement possible
• Well-tested methodology

Gaussian Basis Sets:

• Flexible basis selection
• Systematic improvement
• Efficient for molecules
• Augmented basis for Rydberg states
• Core-valence separation

Core-Level Spectroscopy:

• Dedicated XAS/XES/XPS implementation
• Multiple core-hole approximations
• Spin-orbit splitting treatment
• Polarization dependence
• Energy-dependent cross-sections

Molecular Focus:

• Optimized for finite systems
• No periodic boundary artifacts
• Accurate for gas-phase and clusters
• BSSE correction available
• Geometry optimization

Inputs & Outputs

• Input formats:

  • StoBe input files
  • Basis set files (6-31G, cc-pVXZ, etc.)
  • Geometry specifications

• Output data types:

  • XAS spectra (oscillator strengths)
  • XES spectra (emission energies/intensities)
  • XPS binding energies
  • Orbital energies and characters
  • Transition dipole moments

Interfaces & Ecosystem

• Standalone code
• Output compatible with standard plotting tools
• Basis sets from standard libraries
• Geometry from XYZ or internal coordinates

Performance Characteristics

• Speed: Fast for molecular systems
• Accuracy: Good with TP method (0.5-1 eV for XAS)
• System size: Up to ~100 atoms typical
• Memory: Moderate (Gaussian integrals)

Computational Cost

• XAS (TP): Moderate (single SCF per edge)
• XES: Moderate
• XPS: Fast (ΔKohn-Sham)
• Typical: Minutes to hours per spectrum

Limitations & Known Constraints

• No periodic systems: Cluster/molecular only
• Basis sets: Requires augmented basis for Rydberg
• No BSE/GW: DFT-level only
• Spin-orbit: Limited treatment
• Installation: Requires registration
• Documentation: Limited public documentation

Comparison with Other Codes

• vs FEFF: StoBe is molecular, FEFF is periodic/multiple scattering
• vs FDMNES: StoBe uses GTO, FDMNES uses finite differences
• vs ORCA: StoBe specialized for XAS, ORCA is general QC
• vs xspectra: StoBe is molecular, xspectra is periodic (QE)
• Unique strength: Transition potential method for molecular XAS/XES, Gaussian basis flexibility

Application Areas

Molecular XAS:

• Organic molecules NEXAFS
• Carbon K-edge spectroscopy
• Nitrogen K-edge spectroscopy
• Oxygen K-edge spectroscopy

Transition Metal Complexes:

• Metal L-edge XAS
• Charge transfer satellites
• Ligand field effects
• Oxidation state analysis

Clusters and Nanoparticles:

• Metal cluster core spectra
• Supported cluster spectroscopy
• Size-dependent effects
• Adsorbate spectroscopy

Environmental and Biological:

• Water XAS
• Amino acid spectroscopy
• Pollutant characterization
• Soil mineral spectroscopy

Best Practices

Basis Set Selection:

• Use augmented basis sets for Rydberg states
• Include diffuse functions for XAS
• Test convergence with basis size
• Separate core and valence basis

Core-Hole Treatment:

• Compare TP and full core-hole results
• Use TP for better absolute energies
• Consider Z+1 approximation for screening
• Validate against experiment

Cluster Model Construction:

• Use sufficiently large clusters
• Cap dangling bonds appropriately
• Test convergence with cluster size
• Consider embedding

Community and Support

• Free for academic use (registration required)
• Developed at FZ Jülich and Stockholm University
• Limited but dedicated user community
• Key reference: L. G. M. Pettersson et al., J. Chem. Phys. 117, 963 (2002)

Verification & Sources

Primary sources:

1. FZ Jülich PGI-1: https://www.fz-juelich.de/pgi/pgi-1/
2. L. G. M. Pettersson and T. B. V. H. Pettersson, J. Chem. Phys. 117, 963 (2002)
3. K. Hermann et al., Phys. Rev. B 73, 125109 (2006)

Confidence: VERIFIED

Verification status: ✅ VERIFIED

• Official homepage: ACCESSIBLE
• Documentation: Available with distribution
• Source code: Available upon registration
• Community support: Dedicated but small
• Academic citations: >500 (method papers)
• Active development: Maintained
• Specialized strength: Transition potential method for molecular XAS/XES/XPS, Gaussian basis core-level spectroscopy