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

      Guess vector type. Accepted values are ``UNIT`` for a unit vector guess  :term:`NUM_ROOTS <NUM_ROOTS (DETCI)>` and :term:`NUM_INIT_VECS <NUM_INIT_VECS (DETCI)>` must both be 1); ``H0_BLOCK`` to use eigenvectors from the H0 BLOCK submatrix (default); ``DFILE`` to use NUM_ROOTS previously converged vectors in the D file; 

      * **Type**: string
      * **Possible Values**: UNIT, H0\_BLOCK, DFILE
      * **Default**: H0\_BLOCK

