perturbopy.postproc.utils.constants.conversion_factor

perturbopy.postproc.utils.constants.conversion_factor(init_units, final_units, units_names, units_vals)

Finds the conversion factor between two units.

Parameters:

• init_units (str) – The initial units in the conversion.

• final_units (str) – The final units in the conversion.

• units_names (dict) – A dictionary specifying the standard unit name corresponding to a set of possible units names (case-insensitive). See prefix_and_base_units for details.

• units_vals (dict) –

  A dictionary specifying the conversion factors between different units, with units labeled by their standard name as specified in units_names. Values are represented as tuples (base, exponent).

  Example: For energies, possible units include hartrees and electron-volts.’ Setting one value (hartree = 1), the remaining values

  are the conversion factors between different units and hartrees.

  energy_units_vals = {‘eV’: (2.7211396132, 1), ‘Ha’: (1, 0),’Ry’: (0.5, 0)}

Returns:

conversion_factor – The conversion factor to convert from init_units to final_units.

Return type:

float

Raises:

ValueError – If the base units of init_units or final_units are not in the keys of units_vals

Examples

>>> conversion_factor('fm', 'cm', {m': ['m', 'meter']},
                                  {'m': (5.29177249, -11)})
1e-13
>>> conversion_factor('a.u', 'bohr', {'bohr': ['bohr', 'a.u'], 'angstrom': ['angstrom, a']},
                                     {'bohr': (1, 0), 'angstrom': (0.529177249, 0)})
1.0
>>> conversion_factor('a.u', 'angstrom', {'bohr': ['bohr', 'a.u'], 'angstrom': ['angstrom, a']},
                                         {'bohr': (1, 0), 'angstrom': (0.529177249, 0)})
0.529177249