:term:`CFOUR_NEGEVAL <CFOUR_NEGEVAL (CFOUR)>`
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      Specifies what to do if negative eigenvalues are encountered in the totally symmetric Hessian during an NR or MANR geometry-optimization search. If ABORT (=0), the job will terminate with an error message; if SWITCH (=1) the program will just switch the eigenvalue to its absolute value and keep plugging away (this is strongly discouraged!); and if RFA (=2), the keyword :term:`CFOUR_GEO_METHOD <CFOUR_GEO_METHOD (CFOUR)>` is switched to RFA internally and the optimization is continued. **Psi4 Interface:** Geometry optimizations run through PSI (except in sandwich mode) use PSI's optimizer and so this keyword has no effect. Use :ref:`optking <apdx:optking>` keywords instead.

      * **Type**: string
      * **Possible Values**: ABORT, SWITCH, RFA
      * **Default**: ABORT