Calculation script functions

e_vs_r(lammps_command, system, potential, mpi_command=None, ucell=None, rmin=2.0, rmax=6.0, rsteps=200)

Performs a cohesive energy scan over a range of interatomic spaces, r.

  • lammps_command (str) – Command for running LAMMPS.

  • system (atomman.System) – The system to perform the calculation on.

  • potential (atomman.lammps.Potential) – The LAMMPS implemented potential to use.

  • mpi_command (str, optional) – The MPI command for running LAMMPS in parallel. If not given, LAMMPS will run serially.

  • ucell (atomman.System, optional) – The fundamental unit cell correspodning to system. This is used to convert system dimensions to cell dimensions. If not given, ucell will be taken as system.

  • rmin (float, optional) – The minimum r spacing to use (default value is 2.0 angstroms).

  • rmax (float, optional) – The maximum r spacing to use (default value is 6.0 angstroms).

  • rsteps (int, optional) – The number of r spacing steps to evaluate (default value is 200).


Dictionary of results consisting of keys:

  • ’r_values’ (numpy.array of float) - All interatomic spacings, r, explored.

  • ’a_values’ (numpy.array of float) - All unit cell a lattice constants corresponding to the values explored.

  • ’Ecoh_values’ (numpy.array of float) - The computed cohesive energies for each r value.

  • ’min_cell’ (list of atomman.System) - Systems corresponding to the minima identified in the Ecoh_values.

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Main function called when script is executed directly.

process_input(input_dict, UUID=None, build=True)

Processes str input parameters, assigns default values if needed, and generates new, more complex terms as used by the calculation.

  • input_dict (dict) – Dictionary containing the calculation input parameters with string values. The allowed keys depends on the calculation style.

  • UUID (str, optional) – Unique identifier to use for the calculation instance. If not given and a ‘UUID’ key is not in input_dict, then a random UUID4 hash tag will be assigned.

  • build (bool, optional) – Indicates if all complex terms are to be built. A value of False allows for default values to be assigned even if some inputs required by the calculation are incomplete. (Default is True.)


Calculates the r/a ratio by identifying the shortest interatomic spacing, r, for a unit cell.


ucell (atomman.System) – The unit cell system to evaluate.


The shortest interatomic spacing, r, divided by the unit cell’s a lattice parameter.

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