# CheckpointHandler¶

class CheckpointHandler(file_name=None, time_interval=None)

Class for representing the parameters used for saving the configuration and calculator at regular intervals during self- consistent iterations.

Parameters: file_name (str) – The name of the checkpoint file. The file can be given as an absolute path or a relative path interpreted relative to the current working directory. The path of the checkpoint file is written in the output log of the calculator. The extension can be either “nc” for a NetCDF file or “hdf5” for an HDF5 file. Default: File of the form: 'TEMP/checkpointXXXXXXXX.hdf5', where TEMP is the temporary folder on the computer and X is a random digit. time_interval (PhysicalQuantity of type time interval | Disabled) – The approximate time between saving. The program will check if the time since last save exceeds the time interval after each self-consistent iteration. Default: 0.5 * Hour.
fileName()
Returns: The name of the checkpoint file. str
timeInterval()
Returns: The length of the time interval or Disabledif there’s no checkpoint handling. PhysicalQuantity of type time interval | Disabled

## Usage Examples¶

Set the checkpoint file to “/home/checkpoint.nc” and tell the calculator to store itself every 20 minutes.

checkpoint_handler = CheckpointHandler('/home/checkpoint.nc', 20*Minute)
calculator = LCAOCalculator(checkpoint_handler=checkpoint_handler)


Turn off checkpoint handling for a calculator.

calculator = LCAOCalculator(checkpoint_handler=NoCheckpointHandler)