:term:`CFOUR_FINITE_PERTURBATION <CFOUR_FINITE_PERTURBATION (CFOUR)>`
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

      Specifies the field strength for a perturbation (defined within a ``%perturbation`` section). The value must be given as an integer, and the field strength used by the program will be then the value of the keyword :math:`\times 10^{-6}`.

      * **Type**: integer
      * **Default**: 0

