# CFOUR_NEGEVAL

> 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 CFOUR_GEO_METHOD 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 optking keywords instead.

> - Type: string
> - Possible Values: ABORT, SWITCH, RFA
> - Default: ABORT