Official Resources
- Homepage: https://exciting-code.org/
- Documentation: https://exciting-code.org/carbon-xs-spectroscopy
- Source Repository: https://github.com/exciting-code/exciting
- License: GNU General Public License v2.0
Overview
exciting-XS refers to the X-ray spectroscopy capabilities within the exciting code. It is a full-potential all-electron DFT code based on the linearized augmented plane-wave (LAPW) method. It can calculate core-level spectra (XAS, XES, EELS) using the Bethe-Salpeter Equation (BSE) or Time-Dependent DFT (TDDFT), providing highly accurate descriptions of core excitations including excitonic effects.
Scientific domain: X-ray spectroscopy, core-level excitations, all-electron DFT
Target user community: Spectroscopists, materials scientists requiring high precision
Theoretical Methods
- Full-potential LAPW+lo method
- Bethe-Salpeter Equation (BSE) for core states
- Time-Dependent Density Functional Theory (TDDFT)
- Core-hole interaction (electron-hole attraction)
- Spin-orbit coupling in core states
- All-electron treatment (no pseudopotentials)
Capabilities (CRITICAL)
- Calculation of K, L, M edge XAS and XES
- Solution of the BSE for core excitations (accurate excitonic effects)
- Electron Energy Loss Spectroscopy (EELS) at core edges
- Momentum-dependent excitations (q-dependence)
- Real-space visualization of core excitons
- High-precision results due to LAPW basis
Sources: exciting documentation, Comp. Phys. Comm. 185, 2080 (2014)
Key Strengths
All-Electron Accuracy:
- Full-potential LAPW
- No pseudopotential errors
- Core state treatment
- High precision
BSE for Core Levels:
- Excitonic effects
- Core-hole interaction
- Momentum dependence
- Exciton visualization
Open Source:
- GPL licensed
- GitHub hosted
- Active development
- Good documentation
Inputs & Outputs
- Input formats:
input.xml (comprehensive XML configuration)
- Output data types:
XAS_*.xml (spectra), EPSILON_*.OUT (dielectric function), EXCITON_*.OUT
Interfaces & Ecosystem
- Visualization: Tools to plot XML output
- Cluster: Parallelized (MPI/OpenMP) for HPC
- Tools:
excitingscripts for post-processing
Workflow and Usage
- Perform ground state SCF calculation.
- Configure
input.xml for xs calculation (define edge, screening, BSE parameters).
- Run
exciting_smp or exciting_serial.
- Analyze spectral files.
Performance Characteristics
- Computationally demanding (BSE scaling)
- Requires convergence of empty states
- Highly accurate but slower than pseudopotential methods
Limitations & Known Constraints
- Computational cost: BSE is expensive
- Empty states: Requires convergence
- LAPW complexity: Steeper learning curve
- System size: Limited by cost
Comparison with Other Tools
- vs OCEAN: Both BSE, exciting all-electron
- vs FEFF: exciting periodic, FEFF cluster
- vs xspectra: exciting more accurate, xspectra faster
- Unique strength: All-electron BSE for core levels
Application Areas
- Core-level spectroscopy of complex oxides
- Excitonic effects in insulators and semiconductors
- Anisotropic X-ray absorption
- Core-hole screening physics
Best Practices
- Converge empty states carefully
- Use appropriate k-point mesh
- Test BSE parameters
- Validate with experiment
Community and Support
- Open-source (GPL)
- Developed by exciting team (Humboldt Univ. Berlin, etc.)
- Active forum and tutorials
Verification & Sources
Primary sources:
- Homepage: https://exciting-code.org/
- Publication: A. Gulans et al., J. Phys.: Condens. Matter 26, 363202 (2014)
Confidence: VERIFIED
Verification status: ✅ VERIFIED
- Website: ACTIVE
- Documentation: AVAILABLE
- Source: OPEN (GitHub)
- Development: ACTIVE
- Applications: BSE for core levels, all-electron XAS