nlread(filename, class_type=None, object_id=None, read_state=None)

Function for reading configurations and results from files. The following file types are supported: HDF5 (only from ATK 2017 and later), NetCDF (only from ATK 10.8 and later), GPAW, ASE, XYZ, Python scripts (also from ATK 2008.10 and earlier), CAR and TRAJ (ASE trajectories).

  • filename (str) – The file that objects should be loaded from.
  • class_type (class) – Only load objects of this type (HDF5, NetCDF and GPAW only).
  • object_id (str) – Only load objects that match object_id.
  • read_state (bool) – When read_state is True the self-consistent calculation data is read from configurations when present. Otherwise, configurations will still have a calculator, but the self-consistent data will not be available.
Returns:A list of the objects loaded from the file.
Return type:list

Usage Examples

Restore the self-consistent state of a previous calculation (to save the state, see the Usage Examples for the nlsave function).

# Read self-consistent calculations
molecule_configuration_list = nlread(

# Choose the first configuration in the list
molecule_configuration = molecule_configuration_list[0]

Restore the object with object_id = 'id0' from the NetCDF file bandstructure.hdf5 (to save the state, consult the nlsave function).

molecular_energy_spectrum = nlread(filename='', object_id='id0')

Restore all MolecularEnergySpectrum objects from the file spectrum.hdf5 and select the first object.

molecular_energy_spectrums = nlread(
molecular_energy_spectrum = molecular_energy_spectrums[0]

More details regarding file IO in QuantumATK can be found here.