A **HF stability analysis** is requested via the keyword **HFSTABILITY**.

**HFSTABILITY=ON**

just requests a stability check (**real RHF instabilities**, **real UHF instabilities**, as
well as **magnetic RHF/UHF instabilities**) and provides lowest eigenvalues and eigenvectors for
the corresponding orbital hessians.

**HFSTABILITY=FOLLOW**

requests a stability analysis followed (in the case of a instability) by HF-SCF calculations searching for
a lower solution. Note that these calculations should be performed with **REF=UHF** and **SYM=OFF**, as
otherwise this SCF calculations cannot be properly performed. Default is here to follow the eigenvectors to
the lowest eigenvalue of the orbital hessian, but use of higher-lying negative eigenvectors can be enforced
via

**ROT_EVEC=n**

where **n** specifies the corresponding eigenvector to be followed.

Note that a HF stability analysis can be combined with a correlated calculation and also be used to provide
**symmetry-broken UHF** solutions.

**Examples**

*Instability analysis for RHF wavefunctions*

*Instability analysis for UHF wavefunctions*

*Determination of a UHF solution for unstable RHF case*

*Correlated Calculations using symmetry-broken UHF solutions*

**Recommendations for HF stability analysis calculations**