Any number of optimisation steps can be run with a
single call to OPTIM, as specified by the keyword STEPS.
The default convergence criteria for eigenvector-following and steepest-descent runs are
that the maximum unscaled step size for
any coordinate (or eigenvector, depending upon the scaling criterion) is less
than and the RMS force is also less than .
The number of negative Hessian eigenvalues must also agree with the search type requested.
These convergence criteria can be overruled by the
CONVERGE keyword, as described in §3.