:term:`CFOUR_HFSTABILITY <CFOUR_HFSTABILITY (CFOUR)>`
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      Control analysis of the stability of RHF, ROHF and UHF wavefunctions, as well as a possible search for a lower SCF solution. There are three possible options for this keyword. OFF (=0) does nothing, while ON (=1) performs a stability analysis and returns the number of negative eigenvalues in the orbital rotation Hessian. A third option, FOLLOW (=2) performs the stability analysis and then proceeds to rotate the SCF orbitals in the direction of a particular negative eigenvalue of the orbital rotation Hessian (see the explanation of keyword :term:`CFOUR_ROT_EVEC <CFOUR_ROT_EVEC (CFOUR)>` , after which the SCF is rerun.

      * **Type**: string
      * **Possible Values**: OFF, ON, FOLLOW
      * **Default**: OFF

