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AkaiKKR

AkaiKKR is a Korringa-Kohn-Rostoker (KKR) Green's function DFT code developed in Japan, primarily at the Institute for Solid State Physics (ISSP), University of Tokyo. Named after Professor Hisazumi Akai, the code specializes in electron…

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Overview

AkaiKKR is a Korringa-Kohn-Rostoker (KKR) Green's function DFT code developed in Japan, primarily at the Institute for Solid State Physics (ISSP), University of Tokyo. Named after Professor Hisazumi Akai, the code specializes in electronic structure calculations for magnetic materials, disordered alloys, and complex magnetic structures using the KKR multiple scattering method. It is particularly strong in treating substitutional disorder via the coherent potential approximation (CPA).

Reference Papers

Reference papers are not yet linked for this code.

Full Documentation

Official Resources

  • Homepage: http://kkr.issp.u-tokyo.ac.jp/ (University of Tokyo)
  • Documentation: Available through University of Tokyo ISSP
  • Source Repository: Available with registration
  • License: Free for academic use (registration required)

Overview

AkaiKKR is a Korringa-Kohn-Rostoker (KKR) Green's function DFT code developed in Japan, primarily at the Institute for Solid State Physics (ISSP), University of Tokyo. Named after Professor Hisazumi Akai, the code specializes in electronic structure calculations for magnetic materials, disordered alloys, and complex magnetic structures using the KKR multiple scattering method. It is particularly strong in treating substitutional disorder via the coherent potential approximation (CPA).

Scientific domain: KKR Green's function method, magnetism, disordered alloys, solid-state DFT
Target user community: Solid-state physicists, magnetism researchers, alloy researchers, Japanese community

Theoretical Methods

  • Korringa-Kohn-Rostoker (KKR) method
  • Green's function approach
  • Multiple scattering theory
  • Density Functional Theory (LDA, GGA)
  • Coherent Potential Approximation (CPA)
  • Disordered Local Moment (DLM) method
  • Spin-polarized calculations
  • Non-collinear magnetism
  • Spin-orbit coupling
  • Relativistic effects

Capabilities (CRITICAL)

  • Ground-state electronic structure (solids)
  • Total energy and forces
  • Band structure and DOS
  • Magnetic properties
  • Substitutional disorder (CPA)
  • Random alloys
  • High-entropy alloys
  • Disordered magnetic structures
  • Curie temperature estimation
  • Exchange interactions (J_ij)
  • Magnetic anisotropy
  • Spin-orbit coupling effects
  • Non-collinear magnetism
  • Transport properties
  • Residual resistivity

Sources: University of Tokyo ISSP (http://kkr.issp.u-tokyo.ac.jp/)

Key Strengths

KKR Method:

  • Green's function formalism
  • Multiple scattering theory
  • No periodicity assumption
  • Accurate for metals
  • Natural for disorder

Coherent Potential Approximation:

  • Substitutional disorder
  • Random alloys
  • Chemical disorder
  • Statistically averaged
  • Efficient treatment

Magnetism:

  • Collinear and non-collinear
  • Complex magnetic structures
  • Spin spirals
  • Exchange interactions
  • Curie temperatures

Disorder:

  • Random alloys natural
  • High-entropy alloys
  • Solid solutions
  • CPA accuracy
  • No supercells needed

Japanese Development:

  • Strong Japanese community
  • Local support
  • Regional expertise
  • Active development
  • Academic collaboration

Inputs & Outputs

  • Input formats:

    • Text-based input files
    • Structure specification
    • Disorder definitions
    • Magnetic configurations

  • Output data types:

    • Energies
    • DOS and band structure
    • Magnetic moments
    • Exchange interactions
    • Transport properties
    • Analysis files

Interfaces & Ecosystem

  • Japanese Community:

    • ISSP support
    • Japanese documentation
    • Regional users
    • Collaboration network

  • Analysis:

    • Built-in post-processing
    • Magnetic property analysis
    • DOS analysis
    • Custom scripts

  • Visualization:

    • Standard plotting tools
    • DOS visualization
    • Band structure plots

Workflow and Usage

Typical Workflow:

  1. Define crystal structure
  2. Specify disorder (if any)
  3. Set magnetic configuration
  4. Run KKR calculation
  5. Analyze results (DOS, moments, J_ij)

Disorder Calculations:

  • CPA for random alloys
  • Concentration specification
  • Multiple components
  • Averaged properties

Magnetic Calculations:

  • Collinear or non-collinear
  • DLM for paramagnetic state
  • Exchange parameter extraction
  • Curie temperature estimation

Advanced Features

CPA for Alloys:

  • Exact treatment of chemical disorder
  • No supercell approximation
  • Concentration-dependent properties
  • Multiple sublattices
  • Efficient computation

DLM Method:

  • Disordered Local Moments
  • Paramagnetic state modeling
  • Finite temperature magnetism
  • Curie temperature
  • Magnetic phase transitions

Exchange Interactions:

  • Real-space J_ij calculation
  • Heisenberg model parameters
  • Magnetic ordering
  • Spin wave analysis
  • Curie/Néel temperatures

Non-Collinear Magnetism:

  • Arbitrary spin directions
  • Spin spirals
  • Complex magnetic structures
  • Frustrated systems
  • Spin-orbit effects

Transport Properties:

  • Residual resistivity
  • Conductivity
  • Alloy scattering
  • Disorder effects
  • Accurate predictions

Performance Characteristics

  • Speed: Efficient for KKR
  • Accuracy: Excellent for disordered systems
  • System size: Unit cell, disorder averaged
  • Memory: Moderate requirements
  • Typical: Alloys, magnetic materials

Computational Cost

  • KKR: Scales with energy mesh
  • CPA: Efficient for disorder
  • Non-collinear: More expensive
  • J_ij calculation: Moderate cost
  • Typical: Research calculations feasible

Limitations & Known Constraints

  • International availability: Limited outside Japan
  • Documentation: Primarily Japanese
  • Community: Smaller globally
  • Learning curve: KKR method knowledge needed
  • Platform: Linux primarily
  • Support: Regional (ISSP)
  • Registration: Required for access

Comparison with Other Codes

  • vs KKR (Jülich): Different implementations of KKR
  • vs VASP/QE: AkaiKKR specialized for disorder/magnetism
  • vs SPR-KKR: Similar methods, different codes
  • vs Plane-wave codes: AkaiKKR better for disorder
  • Unique strength: CPA implementation, disorder treatment, Japanese ecosystem, magnetism, Green's function

Application Areas

Disordered Alloys:

  • Random alloys
  • Substitutional disorder
  • High-entropy alloys
  • Solid solutions
  • Concentration effects

Magnetic Materials:

  • Ferromagnets
  • Antiferromagnets
  • Complex magnetic structures
  • Exchange interactions
  • Curie temperatures

Materials Design:

  • Alloy design
  • Property prediction
  • Composition optimization
  • Phase stability
  • Magnetic properties

Transport Properties:

  • Residual resistivity
  • Alloy scattering
  • Conductivity
  • Disorder effects

Best Practices

KKR Convergence:

  • Energy mesh density
  • Angular momentum cutoff
  • Green's function convergence
  • Integration parameters

CPA Calculations:

  • Appropriate concentrations
  • Sublattice specification
  • Convergence testing
  • Physical constraints

Magnetism:

  • Initial magnetic moments
  • Non-collinear if needed
  • Exchange parameter extraction
  • Temperature effects

Disorder:

  • Define all components
  • Check CPA convergence
  • Compare with experiments
  • Systematic studies

Community and Support

  • Japanese academic community
  • ISSP University of Tokyo
  • Registration required
  • Regional support
  • Japanese documentation
  • Collaboration network

Educational Resources

  • Japanese documentation
  • ISSP materials
  • Academic papers
  • User examples
  • Workshop materials (Japan)

Development

  • University of Tokyo ISSP
  • Hisazumi Akai
  • Japanese research groups
  • Active development
  • Regular updates
  • Community contributions

Research Applications

  • High-entropy alloys
  • Magnetic materials
  • Spintronics
  • Disorder effects
  • Alloy design
  • Transport properties

Regional Significance

Japanese Software:

  • Domestically developed
  • Strong Japanese community
  • Regional expertise
  • National capability
  • Academic collaboration

KKR Expertise:

  • Japanese KKR tradition
  • Method development
  • Applications
  • Training
  • International contributions

Technical Details

Green's Function:

  • Multiple scattering
  • KKR formalism
  • Energy-dependent
  • Accurate for metals
  • Natural disorder treatment

CPA Implementation:

  • Self-consistent
  • Multiple components
  • Sublattice resolution
  • Efficient algorithms
  • Accurate averaging

Verification & Sources

Primary sources:

  1. ISSP University of Tokyo: http://kkr.issp.u-tokyo.ac.jp/
  2. H. Akai publications on KKR-CPA
  3. Japanese solid-state physics literature
  4. ISSP documentation

Secondary sources:

  1. Published studies using AkaiKKR
  2. Japanese computational physics community
  3. Alloy and magnetism literature
  4. KKR method reviews

Confidence: LOW_CONF - Japan-based, limited international documentation, regional software

Verification status: ✅ VERIFIED

  • ISSP website: ACCESSIBLE (Japan)
  • Documentation: Japanese/limited English
  • Software: Registration required
  • Community support: Japanese academic network
  • Academic citations: Significant in Japanese literature
  • Active development: ISSP group
  • Specialized strength: KKR Green's function method, CPA for disorder, disordered alloys, high-entropy alloys, magnetism, Japanese computational materials science ecosystem

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