:term:`MIXED4 <MIXED4 (DETCI)>`
"""""""""""""""""""""""""""""""

      Do allow "mixed" excitations involving RAS IV into the CI space. Useful to specify a split-virtual CISD[TQ] computation. If FALSE, then if there are any electrons in RAS IV, then the number of holes in RAS I cannot exceed the given excitation level :term:`EX_LEVEL <EX_LEVEL (DETCI)>`  

      * **Type**: :ref:`boolean <op_c_boolean>`
      * **Default**: true

