Interatomic Force Constants

This example shows how to plot the longitudinal part of the Interatomic Force Constants in real-space starting from a DDB file.

See e.g. <https://journals.aps.org/prb/pdf/10.1103/PhysRevB.50.13035>

Important

Note that a manager.yml configuration file and an abinit installation are required to run this script as AbiPy needs to invoke anaddb to compute the IFCs from the DDB file.

Open the DDB file for AlAs

import os
import abipy.data as abidata

from abipy import abilab

filepath = os.path.join(abidata.dirpath, "refs", "alas_phonons", "trf2_3_DDB")
ddb = abilab.abiopen(filepath)

Call anaddb to compute the Interatomic Force Constants Default args are: asr=2, chneut=1, dipdip=1.

ifc = ddb.anaget_ifc()

Plot the total longitudinal IFCs in local coordinates,

ifc.plot_longitudinal_ifc(title="Total Longitudinal IFCs")

Plot the short range longitudinal IFCs in local coordinates,

ifc.plot_longitudinal_ifc_short_range(title="Longitudinal SR-IFCs")

Plot the Ewald part of the IFCs in local coordinates,

ifc.plot_longitudinal_ifc_ewald(title="Longitudinal LR-IFCs")