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

      Specifies the step length in mass-weighted coordinates (in :math:`10^{-4} amu^{1/2} bohr` ) used in generating the force constant matrix by finite difference of Cartesian gradients.

      * **Type**: integer
      * **Default**: 5

