Thermal_conductivity

This WorkChain is designed to calculate the thermal conductivity with phono3py using an interative procedure by increasing the cutoff distance. This WorkChain makes use of phonon WorkChain to calculate the harmonic band structure and DOS and determine the dynamical stability of the crystal structure. If the crystal structure is stable then it calculates the thermal conductivity using phono3py using a small cutoff distance (defined by the user) and successively increase it until reaching convergence. The convergence criteria are given by the user as atol and rtol parameters. The convergence criteria works in the same manner of numpy allclose function (https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.allclose.html), applied to all values of kappa vs temperature.

ThermalPhono3py(structure, ph_settings, es_settings[, optimize=True, use_nac=False, pressure= 0.0, calculate_fc=False, gp_chunks=1, gp_chunks=10, initial_cutoff=2.0, step=1.0, atol=0.1, rtol=0.3])
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)
  • 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.
  • 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.
  • gp_chunks – (optional) Int object that defines the number of computers in which the calculation will be distributed (default: 1).
  • initial_cutoff – (optional) Float object that defines initial cutoff distance for phono3py calculation.
  • step – (optional) Float object that defines increment of cutoff distance in each iteration.
  • atol – (optional) Float object that defines the convergence criteria of thermal conductivity, absolute value (thermal conductivity units).
  • rtol – (optional) Float object that defines the convergence criteria of thermal conductivity, relative value.

The results outputs of this WorkChain are the following :

  • kappa: ArrayData object that contains the results stored in kappa-mxxx-gx.hdf5 output file.
  • final_structure: StructureData object that contains the optimized unit cell. If no optimization is performed this contains the same StructureData object provided as a input.
  • thermal_properties: ArrayData object that contains the harmonic thermal properties calculated using phonopy. These include the entropy, free energy and heat capacity at constant volume.
  • dos: PhononDosData object that contains the harmonic phonon full and partial density of states.
  • band_structure: BandStructureData object that contains the harmonic phonon band structure.