Convergence criterion, for stopping the minimization. In
units of length; minimization is stopped when the coordinates
of all species change less than GOMinimumMove, or the
GOTolerance criterion is satisfied.
If GOMinimumMove < 0, this criterion is ignored.
Default is -1, except 0.001 b with GOMethod = simplex.
Note that if you use GOMethod = simplex,
then you must supply a non-zero GOMinimumMove.