elphmod

Official Resources

• Homepage: https://janberges.github.io/elphmod/
• Source Repository: https://github.com/janberges/elphmod
• Documentation: https://janberges.github.io/elphmod/
• PyPI: https://pypi.org/project/elphmod/
• License: GPL-3.0

Overview

elphmod is a collection of Python modules to handle coupled tight-binding and mass-spring models derived from first principles. It provides interfaces with Quantum ESPRESSO, Wannier90, EPW, RESPACK, and i-PI for electron-phonon calculations.

Scientific domain: Electron-phonon coupling, phonon calculations, tight-binding models
Target user community: Researchers studying electron-phonon interactions from first principles

Theoretical Methods

• Mass-spring models for phonons
• Tight-binding electronic structure
• Electron-phonon coupling
• Dynamical matrix construction
• Force constant interpolation
• Wannier function integration

Capabilities (CRITICAL)

• Read QE phonon output
• Dynamical matrix manipulation
• Force constant interpolation
• Electron-phonon matrix elements
• Wannier90 integration
• EPW interface
• MPI parallelization
• Supercell calculations

Key Strengths

First-Principles Integration:

• Quantum ESPRESSO interface
• Wannier90 compatibility
• EPW integration
• RESPACK support

Phonon Handling:

• Dynamical matrix I/O
• Force constant processing
• Interpolation methods
• Supercell unfolding

Electron-Phonon:

• Coupling matrix elements
• Transport properties
• Superconductivity calculations
• CDW studies

Inputs & Outputs

• Input formats:

  • QE dynamical matrices
  • Wannier90 files
  • EPW output
  • Force constants

• Output data types:

  • Phonon frequencies
  • Eigenvectors
  • Electron-phonon coupling
  • Transport properties

Interfaces & Ecosystem

• Quantum ESPRESSO: Primary DFT code
• Wannier90: Wannier functions
• EPW: Electron-phonon
• RESPACK: cRPA
• i-PI: Path integral MD

Advanced Features

Electron-Phonon Coupling:

• Matrix element calculations
• Wannier interpolation
• EPW interface for dense meshes
• Superconducting properties (Tc, gap)
• Transport coefficients

Phonon Manipulation:

• Dynamical matrix interpolation
• Force constant real-space representation
• Supercell unfolding
• Long-range corrections
• Acoustic sum rule enforcement

Model Construction:

• Tight-binding Hamiltonians
• Mass-spring models
• Wannier function integration
• Model parameter extraction
• Effective models from DFT

Analysis Tools:

• Spectral functions
• Self-energies
• Green's functions
• Transport properties
• Phase diagram calculations

Performance Characteristics

• Speed: Efficient Python/NumPy (optimized routines)
• Parallelization: MPI support via mpi4py (good scaling)
• Memory: Handles large systems (GBs for dense meshes)
• Scalability: Suitable for production calculations

Computational Cost

• Interpolation: Fast (seconds to minutes)
• Electron-phonon: Moderate (depends on mesh density)
• Transport: Can be expensive (dense k/q meshes)
• Post-processing: Generally efficient

Limitations & Known Constraints

• Primarily QE-focused
• Requires understanding of electron-phonon theory
• Complex setup for beginners
• Documentation evolving

Comparison with Other Codes

• vs EPW: elphmod is Python post-processing; EPW is Fortran calculation
• vs Phonopy: Different focus; elphmod includes electron-phonon
• Unique strength: Unified electron-phonon-lattice framework in Python

Best Practices

Phonon Calculations:

• Ensure converged QE phonons
• Check force constant quality
• Validate interpolation
• Test supercell convergence

Electron-Phonon:

• Use dense k/q meshes
• Check Wannier spread
• Validate coupling strengths

Application Areas

• Superconductivity
• Charge density waves
• Electron-phonon transport
• Phonon-mediated interactions
• 2D materials

Community and Support

• License: Open-source GPL-3.0
• Developer: Jan Berges (active maintainer)
• Development: Regular updates and improvements
• Documentation: Comprehensive with examples
• Zenodo: Archived releases with DOIs
• Publications: Used in peer-reviewed research
• Support: GitHub issues and discussions
• User base: Electron-phonon research community

Verification & Sources

Primary sources:

1. GitHub: https://github.com/janberges/elphmod
2. Documentation: https://janberges.github.io/elphmod/
3. Zenodo: https://doi.org/10.5281/zenodo.5919991

Confidence: VERIFIED

Verification status: ✅ VERIFIED

• Source code: OPEN (GitHub, GPL-3.0)
• Documentation: Comprehensive
• Active development: Yes
• PyPI package: Available