Official Resources
- Homepage: https://anharmonic.github.io/thermal2/
- Source Repository: https://github.com/anharmonic/thermal2
- Documentation: https://anharmonic.github.io/thermal2/
- License: GPL-2.0
Overview
THERMAL2 is a suite of codes for computing lattice thermal conductivity and related anharmonic properties from first principles. It works with third-order force constants from D3Q or other sources to solve the phonon Boltzmann transport equation.
Scientific domain: Thermal transport, phonon BTE, lattice thermal conductivity
Target user community: Researchers computing thermal conductivity from first principles
Theoretical Methods
- Phonon Boltzmann Transport Equation
- Relaxation time approximation
- Variational solution
- Wigner transport equation
- Three-phonon scattering
- Isotope scattering
Capabilities (CRITICAL)
- Lattice thermal conductivity
- Phonon lifetimes and linewidths
- Variational BTE solution
- Wigner conductivity (quantum corrections)
- Isotope scattering
- Grain boundary scattering
- Temperature-dependent properties
Key Strengths
Multiple Methods:
- RTA and variational
- Wigner corrections
- Various scattering mechanisms
- Flexible approach
D3Q Integration:
- Seamless workflow
- QE compatibility
- DFPT force constants
- Consistent methodology
Inputs & Outputs
-
Input formats:
- D3Q force constants
- Dynamical matrices
- Configuration files
-
Output data types:
- Thermal conductivity tensor
- Phonon lifetimes
- Scattering rates
- Mode contributions
Interfaces & Ecosystem
- D3Q: Third-order force constants
- Quantum ESPRESSO: DFT/DFPT
- q2r.x: Force constant processing
Advanced Features
- Variational BTE: Beyond relaxation time approximation
- Wigner transport: Quantum corrections to thermal conductivity
- Multiple scattering: Three-phonon, isotope, grain boundary
- D3Q integration: Seamless workflow with DFPT force constants
- Mode-resolved analysis: Detailed phonon contributions
Performance Characteristics
- BTE solution: Fast (minutes to hours)
- Depends on q-point grid density
- Efficient for QE-based workflows
Computational Cost
- D3Q force constants: Dominant cost (external)
- THERMAL2 BTE solution: Fast (minutes)
- Variational method slightly more expensive than RTA
- Overall: Efficient once force constants available
Best Practices
- Validate harmonic phonons before anharmonic calculations
- Converge q-point grid systematically
- Compare RTA and variational results
- Check isotope scattering contributions
- Validate against experimental thermal conductivity
Limitations & Known Constraints
- Primarily for D3Q workflow
- Requires anharmonic force constants
- Complex for beginners
- QE-centric
Application Areas
- Thermal conductivity predictions
- Thermoelectric materials
- Phonon engineering
- Heat management materials
Verification & Sources
Primary sources:
- Website: https://anharmonic.github.io/thermal2/
- L. Paulatto et al., Phys. Rev. B 91, 054304 (2015)
Confidence: VERIFIED
Verification status: ✅ VERIFIED
- Source code: OPEN (GitHub, GPL-2.0)
- Documentation: Available
- Active development: Yes