Band structure and DOS from Phonopy input

Read force constants from Phonopy output (NaCl: phonopy.yaml + FORCE_CONSTANTS + BORN) as a PythonJob, then reuse the same DispersionWorkChain and DosWorkChain – they accept a force_constants node, so nothing about them is CASTEP-specific.

Set up AiiDA

from _aiida_setup import example_data, get_python_code, show_provenance
from aiida import orm
from aiida.engine import run_get_node
from aiida_pythonjob import PythonJob

code = get_python_code()

Read force constants from Phonopy

A PythonJob stages the Phonopy files and returns a ForceConstantsData node.

from aiida_pythonjob_ins.pythonjobs import prepare_read_phonopy_inputs

read_results, _ = run_get_node(
    PythonJob,
    **prepare_read_phonopy_inputs(
        summary=example_data("phonopy", "NaCl_default", "phonopy.yaml"),
        force_constants=example_data("phonopy", "NaCl_default", "FORCE_CONSTANTS"),
        born=example_data("phonopy", "NaCl_default", "BORN"),
        code=code,
    ),
)
force_constants = read_results["result"]
print(f"Force constants: {force_constants.get_force_constants().crystal.n_atoms} atoms")

Written to /tmp/tmp31g5bnr8/euphonic_object.json
Force constants: 8 atoms

Band structure

Feed the Phonopy-derived force constants straight into the dispersion workflow.

from aiida.plugins import WorkflowFactory

# Load via WorkflowFactory (direct imports like
# `from aiida_pythonjob_ins.workflows import ...` also work)
DispersionWorkChain = WorkflowFactory("pythonjob_ins.dispersion")
DosWorkChain = WorkflowFactory("pythonjob_ins.dos")

bands_results, bands_node = run_get_node(
    DispersionWorkChain,
    force_constants=force_constants,
    q_spacing=orm.Float(0.1),
    code=code,
)
bands_results["band_structure"].show_mpl()

/home/runner/work/aiida_pythonjob_ins/aiida_pythonjob_ins/.venv/lib/python3.12/site-packages/seekpath/getpaths.py:427: SupercellWarning: The provided cell is a supercell: the returned k-path is the standard k-path of the associated primitive cell in the basis of the supercell reciprocal lattice.
  warnings.warn(
Written to /tmp/tmpq2cvb2mk/euphonic_object.json

Density of states

dos_results, _ = run_get_node(
    DosWorkChain,
    force_constants=force_constants,
    q_spacing=orm.Float(0.2),
    energy_spacing=orm.Float(1.0),
    code=code,
)

import matplotlib.pyplot as plt

dos = dos_results["dos"]
_, energy, energy_unit = dos.get_x()
((_, density, dos_unit),) = dos.get_y()

fig, ax = plt.subplots()
ax.plot(energy, density)
ax.set_xlabel(f"Energy ({energy_unit})")
ax.set_ylabel(f"Density of states ({dos_unit})")
ax.set_title("NaCl phonon DOS (from Phonopy)")
fig.tight_layout()

Provenance

The graph traces the band structure back through the dispersion workflow to the Phonopy read job – the full history in one picture.

show_provenance(bands_node, title="Phonopy -> dispersion provenance")

<Figure size 1200x1030.26 with 1 Axes>