`statpt` automatically takes the best choice of the Hessian from the
`control` file. For minimizations it first looks for the exact
Hessian and then for the UFF Hessian. If none of them is found it
takes the scaled unit matrix. For transition state optimization the
exact Hessian has a higher priority than the results of LES.

The results of LES can be used to obtain an initial Hessian matrix for
transition state optimizations involving large molecules, where
calculation of the full Hessian is too expensive. Note, that LES
calculations for `statpt`, in addition to the `$les` keyword
require the following keywords to be added *manually* in the
`control` file:

$h0hessian $nomw

The default Hessian update for minimization is `bfgs`

, which is
likely to remain positive definite. The `powell`

update is the
default for transition state optimizations, since the Hessian can
develop a negative curvature as the search progresses.