:term:`REFERENCE <REFERENCE (SCF)>`
"""""""""""""""""""""""""""""""""""

      Reference wavefunction type. **Cfour Interface:** Keyword translates into :term:`CFOUR_REFERENCE <CFOUR_REFERENCE (CFOUR)>` 

      * **Type**: string
      * **Possible Values**: RHF, ROHF, UHF, CUHF, RKS, UKS
      * **Default**: RHF

