:term:`S <S (DETCI)>`
"""""""""""""""""""""

      The value of the spin quantum number :math:`S` is given by this option. The default is determined by the value of the multiplicity. This is used for two things: (1) determining the phase of the redundant half of the CI vector when the :math:`M_s = 0` component is used (i.e., :term:`MS0 <MS0 (DETCI)>` = ``TRUE``), and (2) making sure the guess vector has the desired value of :math:`\langle S^2\rangle` (if :term:`S_SQUARED <S_SQUARED (DETCI)>` is ``TRUE`` and :term:`ICORE <ICORE (DETCI)>` = ``1``).

      * **Type**: double
      * **Default**: 0.0