Official Resources
- Source Repository: https://github.com/rubel75/mstar
- Documentation: Included in repository
- License: Open source
Overview
mstar is a tool for calculating effective masses with DFT using perturbation theory. It computes conductivity, density-of-states, and cyclotron effective masses from WIEN2k band structures using the k·p perturbation theory approach, providing more accurate effective masses than finite-difference methods.
Scientific domain: Effective mass calculation, semiconductor band structure analysis
Target user community: Researchers studying carrier effective masses in semiconductors and insulators
Theoretical Methods
- k·p perturbation theory for effective masses
- Conductivity effective mass (m*_c)
- Density-of-states effective mass (m*_dos)
- Cyclotron effective mass (m*_cyc)
- Principal components of inverse mass tensor
- WIEN2k band structure input
Capabilities (CRITICAL)
- Conductivity effective mass calculation
- Density-of-states effective mass
- Cyclotron effective mass
- Inverse mass tensor principal components
- Perturbation theory approach (more accurate than finite differences)
- WIEN2k interface
Sources: GitHub repository, Comp. Phys. Commun.
Key Strengths
Perturbation Theory:
- More accurate than finite-difference methods
- Systematic convergence
- No numerical differentiation errors
- Well-defined at band extrema
Multiple Mass Definitions:
- Conductivity mass (transport)
- DOS mass (thermodynamics)
- Cyclotron mass (cyclotron resonance)
- Anisotropic mass tensor
WIEN2k Integration:
- Direct interface with WIEN2k
- Uses same basis sets
- Consistent calculation flow
Inputs & Outputs
-
Input formats:
- WIEN2k band structure output
- k-point specifications
-
Output data types:
- Conductivity effective mass (m0/m*_c)
- DOS effective mass
- Cyclotron effective mass
- Principal components of inverse mass tensor
Interfaces & Ecosystem
- WIEN2k: DFT backend
- Fortran: Core computation
Performance Characteristics
- Speed: Fast (post-processing)
- Accuracy: High (perturbation theory)
- System size: Limited by WIEN2k
- Memory: Low
Computational Cost
- Effective mass: Seconds
- WIEN2k pre-requisite: Hours (separate)
- Typical: Very efficient
Limitations & Known Constraints
- WIEN2k only: No VASP or QE support
- Band extrema only: Requires identified extrema
- Perturbation theory: Limited to parabolic regions
- Documentation: Limited
Comparison with Other Codes
- vs effmass: mstar uses perturbation theory, effmass uses finite differences from VASP
- vs emc: mstar is WIEN2k, emc is VASP/QE finite differences
- vs Effective-mass-fitting: mstar is perturbation theory, fitting is polynomial
- Unique strength: Perturbation theory effective masses from WIEN2k, multiple mass definitions
Application Areas
Semiconductor Physics:
- Carrier effective mass for transport
- DOS mass for thermodynamic properties
- Cyclotron mass for magneto-optics
- Anisotropic mass for device modeling
Thermoelectric Materials:
- DOS mass for Seebeck coefficient
- Conductivity mass for electrical conductivity
- Mass anisotropy for direction-dependent transport
- Effective mass optimization
Optoelectronic Materials:
- Reduced mass for exciton binding
- Effective mass for optical absorption
- Carrier mobility estimation
- Band structure engineering
Best Practices
WIEN2k Setup:
- Use well-converged SCF calculation
- Adequate k-point density near extrema
- Include spin-orbit coupling if needed
- Use consistent settings
Mass Calculation:
- Identify band extrema correctly
- Use sufficient k-points near extrema
- Compare perturbation vs finite difference
- Validate against experimental cyclotron resonance
Community and Support
- Open source on GitHub
- Developed by O. Rubel
- Published in Comp. Phys. Commun.
- Research code
Verification & Sources
Primary sources:
- GitHub: https://github.com/rubel75/mstar
- O. Rubel, F. Tran, X. Rocquefelte, and P. Blaha, Comp. Phys. Commun. (related)
Confidence: VERIFIED
Verification status: ✅ VERIFIED
- Source code: ACCESSIBLE (GitHub)
- Documentation: Included in repository
- Published methodology: Comp. Phys. Commun.
- Specialized strength: Perturbation theory effective masses from WIEN2k, multiple mass definitions