auto-kappa v1.1.1

auto-kappa is an automated framework for performing first-principles calculations of anharmonic phonon properties, including

• lattice thermal conductivity,
• mode-dependent phonon lifetimes,
• three-phonon and four-phonon scattering,

using VASP and ALAMODE.
It provides a streamlined pipeline that generates input files, submits calculations, checks convergence, and post-processes results automatically.

Requirements

Users of auto-kappa need to install VASP and ALAMODE in advance, while the required Python libraries are installed automatically along with auto-kappa.

• VASP : 6.3.0 or later
• ALAMODE : 1.4 or 1.5 (1.5 recommended) *
• [Optional] anphon : 1.9.9 (required for four-phonon scattering)
• Python : 3.9 or later
• Phonopy : 2.45.1
• ASE : 3.26.0
• Pymatgen : 2025.10.7
• Spglib : 2.6.0
• Custodian : 2025.5.12

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* Note: The force constant file format in ALAMODE 1.4 is incompatible with that of version 1.5. Therfore, version 1.5 is recommended.

Installation

Follow these steps to install the package:

1. git clone https://github.com/phonix-db/auto-kappa.git
2. cd ./auto-kappa
3. sh install.sh

After installation, ensure that the akrun command is available. You can view a description of the input parameters by running akrun -h.

Preparation

You can perform a simple calculation following the steps below. Please refer to example jobs in auto_kappa/examples and the manual for details.

1. Set the VASP_PP_PATH environment variable so that ASE can locate VASP pseudopotential files: (Pseudopotential with ASE)

ASE expects the pseudopotential files to be in ${VASP_PP_PATH}/potpaw_PBE/{element name}.

2. Prepare a structure file, e.g., POSCAR.Si
3. Run the following command: akrun --file_structure POSCAR.Si --outdir Si.

Several Important Options

You can view the available options by running akrun -h as well as in the manual. Frequently used commands are listed below.

• file_structure: Structure file name. Different formats, including POSCAR and CIF, are accepted.

• outdir: Name of the output directory

• mpirun: MPI command [Default: mpirun]

• nprocs: Number of processes for the calculation [Default: 2]

• command_{vasp/vasp_gam/alm/anphon/anphon_ver2}: Command to run VASP, alm, and anphon [Default: vasp, vasp_gam, alm, anphon, anphon.2.0]

• volume_relaxation: Perform relaxation calculations using the Birch-Murnaghan equation of state [Default: 1]

• analyze_with_larger_supercell: Use a larger supercell when imaginary frequencies appear [Default: 0]

• max_natoms: Maximum number of atoms in the supercell used for the force constant calculation [Default: 150]

• nmax_suggest: Maximum number of displacement patterns for the finite-displacement method. If the number of generated patterns exceeds this value, the LASSO regression approach will be applied [Default: 100].

• scph: Flag for considering phonon renormalization using the self-consistent phonon (SCPH) approach [Default: 0]

• four: Flag for considering four phonon scattering. The "command_anphon_ver2" option must be set properly. [Default: 0]

Documentation

For more details on auto-kappa, please visit the following webpage: HERE.

Workflow

scph	four	No imag. freq. with initial SC	No imag. freq. after SCPH	Use larger SC	FC2 [kappa(init SC)]	FC2 [kappa(larger SC)]	Anharmonic FCs	kappa(init SC)	kappa(larger SC)
0	0	TRUE	-	×	init SC	-	FC3(init SC)	3ph	-
0	1	TRUE	-	×	init SC	-	Higher(init SC)	4ph	-
1, 2	0	TRUE	-	×	renorm(init SC)	-	Higher(init SC)	SCPH+3ph	-
1, 2	1	TRUE	-	×	renorm(init SC)	-	Higher(init SC)	SCPH+4ph	-
0	0	FALSE	-	○	-	larger SC	FC3(init SC)	-	3ph
0	1	FALSE	-	○	-	larger SC	Higher(init SC)	-	4ph
1	0	FALSE	TRUE	×	renorm(init SC)	-	Higher(init SC)	SCPH	-
1	1	FALSE	TRUE	×	renorm(init SC)	-	Higher(init SC)	SCPH+4ph	-
1, 2	0	FALSE	FALSE	○	-	renorm(larger SC)	Higher(init SC)	-	SCPH
1, 2	1	FALSE	FALSE	○	-	renorm(larger SC)	Higher(init SC)	-	SCPH+4ph
2	0	FALSE	TRUE	○	renorm(init SC)	renorm(larger SC)	Higher(init SC)	SCPH	SCPH
2	1	FALSE	TRUE	○	renorm(init SC)	renorm(larger SC)	Higher(init SC)	SCPH+4ph	SCPH+4ph

• init SC: Initial supercell determined by --max_natoms.
• larger SC: Larger supercell determined by parameters such as --delta_max_natoms.
• kappa(init/larger SC): Thermal conductivity calculated using the initial/larger supercell.
• FC2 [kappa(init/larger SC)]: Harmonic force constants (FC2) used to compute kappa(init/larger SC).
• renorm(init/larger SC): Renormalized harmonic force constants (FC2) derived from the FC2 calculated with the initial/larger supercell.
• FC3/Higher(init SC): Cubic and higher-order force constants, always computed using the initial supercell.
• SCPH: Self-consistent phonon (SCPH) calculation.

Citation

If you use auto-kappa, please cite the following paper, along with any related papers listed in the references:

• Masato Ohnishi, Tianqi Deng, Pol Torres, Zhihao Xu, Terumasa Tadano, Haoming Zhang, Wei Nong, Masatoshi Hanai, Zeyu Wang, Michimasa Morita, Zhiting Tian, Ming Hu, Xiulin Ruan, Ryo Yoshida, Toyotaro Suzumura, Lucas Lindsay, Alan J. H. McGaughey, Tengfei Luo, Kedar Hippalgaonkar, and Junichiro Shiomi, "Database and deep-learning scalability of anharmonic phonon properties by automated brute-force first-principles calculations," npj Computational Materials 12, 150 (2026) s41524-026-02033-w.

References

• ALAMODE: T. Tadano, Y. Gohda, and S. Tsuneyuki, J. Phys.: Condens. Matter 26, 225402 (2014).

• ALAMODE (SCP): T. Tadano and S. Tsuneyuki, Phys. Rev. B 92, 054301 (2015).

• VASP: G. Kresse, and J. Furthmuller, Phys. Rev. B 54, 11169-11186 (1996).

• Spglib: A. Togo, K. Shinohara, and I. Tanaka, Sci. technol. adv. material, Meth. 4, 1 (2025).

• SeeK-path: Y. Hinuma, G. Pizzi, Y. Kumagai, F. Oba, and I. Tanaka, Comp. Mat. Sci. 128, 140 (2017).

• Phonopy: A. Togo and I. Tanaka, Scr. Mater., 108, 1-5 (2015).

• Pymatgen and Custodian: S. P. Ong et al., Comp. Mater. Sci. 68, 314-319 (2013).

• ASE: A. H. Larsen et al., J. Phys.: Cond. Matter 29, 273002 (2017).

Developpers

• Tianqie Deng, Michimasa Morita, Wei Nong, Masato Ohnishi, Terumasa Tadano, Pol Torres, Zeyu Wang

(alphabetical order)