principia_materia.phonon_id.little_group_adt module

class principia_materia.phonon_id.little_group_adt.LittleGroupADT(structure, pg, Qpoint, tol=1e-06)

Bases: AnalyticDynamicTensor

Little group analytic representation of dynamic tensor under group theory.

It works under the little group scheme, which is the point group that only maps each q in Q-set into itself. Then it uses this little group to find the irrep decomposition of each q, perform symmetric product and for the ones that contain identity, find the coefficients in the expansion in terms of symmetric basis products. The symmetric basis vectors will be later used for rotating the tensor from symmetric basis to naive basis.

Parameters:

  • structure (CrystalFTG object or a structure file of CrystalFTG) – The crystal structure.

  • pg (str or PointGroup object) – The point group.

  • Qpoint (array of Fraction or a parse_array supported Fraction array.) – The Q-point

  • tol (float, optional, default to 1.0E-6) – Error tolerence.

set_irreducible_derivatives(conjugate=False)

The irreducible derivatives is constructued as well as the coefficients for them in the symmetrized basis.

set_qpoint_displacement_rep()

Find all irreducible derivatives allowed in the given Qpoint and PointGroup.

principia_materia.phonon_id.little_group_adt.get_LittleGroupADT_from_hdf5(h5file, tol=1e-06)

Read data from HDF5 file and construct a LittleGroupADT object.

Parameters:

  • h5file (str or h5py.File/h5py.Group obejct) – Path to a HDF5 file or a h5py.File/h5py.Group object.

  • tol (float, optional, default to 1.0E-6) – Error tolerance to use when constructing the LittleGroupADT object.

principia_materia.phonon_id.little_group_adt.inverse_qpoint(qpoint)
principia_materia.phonon_id.little_group_adt.save_LittleGroupADT_to_hdf5(obj, h5file='little_group_adt.hdf5', overwrite=False)

Save data of a LittleGroupADT object into a HDF5 file.

Parameters:

  • obj (LittleGroupADT) – A LittleGroupADT object.

  • h5file (str or h5py.File/h5py.Group obejct, optional, default to "little_group_adt.hdf5") – Path to a HDF5 file or a h5py.File/h5py.Group object.

  • overwrite (bool, optional, default to False) – When the file exists, whether to replace the content of the file with the content to be saved.