QHA

This WorkChain performs a quasi-harmonic approximation calculation using Phonopy. This WorkChain requires one of the plugins for VASP, QuantumESPRESSO and LAMMPS described in phonon WorkChain. Non-analytical corrections can be included from the Born effective charges and dielectric tensor which are only implemented for VASP plugin. Phonopy can be used either locally and remotely. To use phonopy remotely phonopy code must be setup as described in AiiDA documentation (https://aiida-core.readthedocs.io/en/latest/get_started/index.html#code-setup-and-configuration). using the phonopy plugin provided in this package.

QHAPhonopy(structure, ph_settings, es_settings[, optimize=True, use_nac=False, num_expansions=10])
Parameters:
  • structure – StructureData object that contains the crystal unit cell structure.
  • ph_settings – Dict 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)
  • num_expansions – (optional) IntData object. The number of volume expansions around the optimized structure at zero pressure to perform. By default the value is 10.
  • use_nac – (optional) BooleanData object. Determines if non-analytical corrections will be included in the phonon calculations. By default this option is False.

The results outputs of this WorkChain are the following :

  • qha_results: ArrayData object that contains the thermal properties at constant pressure calculated using phonopy. This ArrayData includes the following arrays: qha_temperatures, helmholtz_volume, thermal_expansion, volume_temperature, heat_capacity_P_numerical, volume_expansion and gibbs_temperature.