Official Resources
- Homepage: https://sites.google.com/view/kazuma7k6r
- Documentation: Official website and GitHub
- Source Repository: https://github.com/respack-dev/respack
- License: GNU General Public License v3.0
Overview
RESPACK is a first-principles calculation software for evaluating interaction parameters in correlated electron systems. Developed in Japan (primarily at University of Tokyo), RESPACK calculates screened Coulomb interactions, constrained RPA parameters, and downfolding for effective models. The code bridges ab-initio calculations and many-body physics, providing interaction parameters for DMFT, model Hamiltonians, and GW calculations.
Scientific domain: Interaction parameters, constrained RPA, effective models
Target user community: Many-body physics, DMFT users, model construction
Theoretical Methods
- Constrained Random Phase Approximation (cRPA)
- GW approximation
- Screened Coulomb interactions
- Downfolding procedures
- Effective interaction parameters
- Wannier function based
Capabilities (CRITICAL)
Category: Open-source interaction parameter calculator
- Constrained RPA (cRPA)
- Screened Coulomb interactions
- Hubbard U calculation
- GW calculations
- Downfolding for models
- DFT interface (Quantum ESPRESSO, xTAPP, VASP)
- Wannier90 integration
- DMFT parameter input
- Production quality
Sources: Official website, GitHub, publications
Key Strengths
Interaction Parameters:
- cRPA for effective U
- Screened interactions
- Material-specific parameters
- DMFT input
- Model Hamiltonians
First-Principles:
- ab-initio based
- DFT integration
- Wannier functions
- Realistic materials
- Production quality
Japanese Development:
- University of Tokyo
- Japanese HPC integration
- Active community
- Research quality
- Well-maintained
GW Calculations:
- GW method
- Quasiparticle energies
- Band gap corrections
- Spectroscopy
Inputs & Outputs
-
Input formats:
- DFT wavefunctions
- Wannier90 models
- Configuration files
-
Output data types:
- Interaction parameters (U, J)
- Screened Coulomb matrix
- GW self-energies
- Effective models
- DMFT inputs
Interfaces & Ecosystem
DFT Codes:
- Quantum ESPRESSO
- xTAPP
- VASP
- Wannier90 integration
Downstream:
- DMFT codes
- Model Hamiltonians
- Many-body calculations
Workflow and Usage
Basic cRPA Workflow:
# 1. DFT calculation
# (Quantum ESPRESSO or other)
# 2. Wannier90 for target orbitals
wannier90.x ...
# 3. RESPACK calculation
calc_chiqw # Polarization
calc_w0 # Screened interaction
calc_j3d # cRPA interaction
# 4. Extract U, J parameters
Configuration:
# Input file example
&PARAM_CALC_CHIQW
Ncond = 100
Nval = 50
Ecutpol = 5.0
/
&PARAM_CALC_W0
Ecutchi = 10.0
/
Output Usage:
# Use calculated U, J in DMFT
U_crpa = 4.5 # eV (from RESPACK)
J_crpa = 0.8 # eV
# Input to DCore, TRIQS, etc.
Advanced Features
cRPA:
- Constrained RPA
- Target orbital specification
- Screening calculation
- Material-specific U
- DMFT parameters
GW:
- Quasiparticle calculations
- Band structure corrections
- Self-energy
- Spectral functions
Downfolding:
- Effective model construction
- Low-energy physics
- Wannier basis
- Model parameters
Performance Characteristics
- Speed: DFT-like scaling
- Accuracy: First-principles
- Purpose: Interaction parameters
- Typical: Hours to days
Computational Cost
- Similar to DFT/GW
- Polarization calculation expensive
- HPC recommended
- Production capable
Limitations & Known Constraints
- Computational cost: Expensive
- DFT input: Requires DFT code
- Expertise: cRPA knowledge needed
- Learning curve: Moderate to steep
- Japanese origin: Some Japanese docs
Comparison with Other Tools
- Unique for: cRPA ab-initio U
- vs empirical U: RESPACK first-principles
- vs DMFT codes: RESPACK provides inputs
- Specialized: Interaction parameter specialist
Application Areas
DMFT Calculations:
- Material-specific U, J
- Realistic parameters
- Correlated materials
- ab-initio DMFT
Model Construction:
- Effective Hamiltonians
- Hubbard models
- Downfolded models
- Low-energy physics
Correlated Materials:
- Transition metal oxides
- f-electron systems
- Strongly correlated
- Realistic calculations
Best Practices
Workflow:
- Quality DFT starting point
- Proper Wannier functions
- Target orbital selection
- Convergence testing
Parameters:
- Energy cutoffs
- Band numbers
- k-point convergence
- Validation
Usage:
- Understand cRPA theory
- Appropriate target orbitals
- Compare with experiment
- DMFT integration
Community and Support
- Open-source (GPL v3)
- Japanese community
- GitHub repository
- University of Tokyo
- Active development
- Publications
Educational Resources
- Official documentation
- Example calculations
- cRPA literature
- Publication list
- Tutorial materials
Development
- University of Tokyo (ISSP)
- Kazuma Nakamura (lead)
- Active development
- Japanese HPC
- Research-driven
Research Impact
RESPACK enables first-principles calculation of interaction parameters for DMFT and many-body calculations, advancing realistic correlated electron simulations from ab-initio.
Verification & Sources
Primary sources:
- Homepage: https://sites.google.com/view/kazuma7k6r
- GitHub: https://github.com/respack-dev/respack
- Publications: Comp. Phys. Comm. 198, 213 (2016)
Secondary sources:
- cRPA literature
- DMFT papers
- User publications
Confidence: VERIFIED - Interaction parameter calculator
Verification status: ✅ VERIFIED
- Website: ACTIVE
- GitHub: ACCESSIBLE
- License: GPL v3 (open-source)
- Category: Interaction parameter calculator
- Status: Actively developed
- Institution: University of Tokyo (ISSP)
- Specialized strength: Constrained RPA for effective interaction parameters, screened Coulomb interactions, Hubbard U from first principles, GW calculations, downfolding, DMFT parameter input, Wannier90 integration, Japanese development, production quality for correlated materials