5. Input Files

NEP-kappa supports two input modes:

  • input-file mode

  • command-line mode

The option names are the same in both modes.

5.1. Input file format

Example:

NEP + phono3py

--poscar      Structure/POSCAR
--nep_model   NEP/Si_2025_Xuke.txt
--do_relax    false
--dim         4 4 1
--fc2fc3      true
--use_hiphive false
--mesh        21 21 1
--temps       100 1000 50
--method      rta
--wigner      true

NEP + HiPhive + phono3py

--poscar      Structure/POSCAR
--nep_model   NEP/Si_2025_Xuke.txt
--do_relax    false
--dim         4 4 1
--fc2fc3      true
--use_hiphive false
--mesh        21 21 1
--temps       100 1000 50
--method      rta
--wigner      true
--n_structures 500
--rattle_std   0.03
--min_dist     2.2
--cutoffs      5.0 4.0

5.2. Rules

  • One option per line is recommended

  • Values are separated by spaces

  • # starts a comment

5.3. Parameter reference

5.3.1. --poscar

Path to the input structure file.

Type: string Default: POSCAR

Example:

--poscar Structure/POSCAR

5.3.2. --nep_model

Path to the NEP model file.

Type: string Required: yes

Example:

--nep_model NEP/Si_2025_Xuke.txt

5.3.3. --do_relax

Whether to relax the structure before force-constant generation.

Type: boolean Default: false

Example:

--do_relax true

5.3.4. --dim

Supercell dimensions for force-constant calculations.

Type: three integers Default: 4 4 1

Example:

--dim 4 4 1

5.3.5. --use_hiphive

Select the force-constant generation route.

Type: boolean Default: false

  • false: finite displacement

  • true: HiPhive

5.3.6. --n_structures

Number of rattled structures used in HiPhive fitting.

Type: integer Default: 50

Example:

--n_structures 100

5.3.7. --rattle_std

Standard deviation of random displacements in HiPhive.

Type: float Default: 0.03

Example:

--rattle_std 0.03

5.3.8. --cutoffs

Cutoff distances used in HiPhive cluster-space construction.

Type: one or more floats Default: 5.0

Examples:

--cutoffs 5.0

--cutoffs 5.0 4.0

5.3.9. --min_dist

Minimum allowed interatomic distance for rattled structures.

Type: float Default: 2.0

Example:

--min_dist 2.0

5.3.10. --mesh

q-point mesh used by phono3py.

Type: three integers Default: 21 21 1

Example:

--mesh 21 21 1

5.3.11. --temps

Temperature setting.

Accepted formats:

Single temperature:

--temps 300

Temperature range:

--temps 100 1000 50

Rule:

  • one value: single temperature

  • three values: tmin tmax tstep

5.3.12. --fc2fc3

Whether to recompute force constants.

Type: boolean Default: false

  • true: recompute fc2.hdf5 and fc3.hdf5

  • false: reuse existing force constants

5.3.13. --method

Thermal conductivity solution method.

Type: string Choices: lbte, rta Default: lbte

5.3.14. --wigner

Whether to enable the Wigner option in phono3py.

Type: boolean Default: false