This WorkChain calculated the 3rd order force constants using phono3py. This WorkChain requires one of the plugins for VASP, QuantumESPRESSO and LAMMPS described in phonon WorkChain. Non-analytical corrections can be calculated from the Born effective charges and dielectric tensor which are only implemented for VASP plugin.

PhononPhono3py(structure, ph_settings, es_settings[, optimize=True, use_nac=False, pressure= 0.0, calculate_fc=False])
  • structure – StructureData object that contains the crystal unit cell structure.
  • ph_settings – Dict data object that contains the phonopy input parameters.
  • es_settings – Dict object that contains the calculator input parameters. These parameters depends on the code used (see workchains/launcher examples)
  • use_nac – (optional) BooleanData object. Determines if non-analytical corrections will be included in the phonon calculations. By default this option is False.
  • optimize – (optional) BooleanData object. Determines if a crystal unit cell optimization is performed or not before the phonon calculation. By default this option is True.
  • pressure – (optional) FloatData object. If optimize is True, this sets the external pressure (in kB) at which the unit cell optimization is preformed. By default this option takes value 0 kB.
  • calculate_fc – (optional) BooleanData object. Determines if the 2on and 3rd order force constants are calculated. By default this option is False.
  • chunks – (optional) Int object that defines the maximum number of calculation to submit simultaneously. The next set of calculation will not be submitted until the previous set is finished.
  • data_sets – (optional) ForceSets object that contains the forces and displacements of a previously calculation. This data_set can be the output of either phonon3 or phonon WorkChains.

The results outputs of this WorkChain are the following :

  • data_sets: ForceSetsData object that contains the information of supercells with displacements and forces. Check
  • force_constants_2order: ForceConstantsData object that contains the 2ond order force constants.
  • force_constants_3order: ForceConstantsData object that contains the 3rd order force constants.
  • final_structure: StructureData containing the optimized structure.

The ForceSetsData object obtained as a output of phonon3 WorkChain can be also in harmonic phonon calculation without modification.