Follow-up Comment #2, bug #22033 (project relax): There used to be a catch for this with a RelaxError. The problem is that we do not have gradients (or Hessians) derived and hardcoded into the dispersion target function code. Therefore Levenberg-Marquardt will not work, nor any of the more advanced algorithms (Newton optimisation for example). Numerical gradients could be calculated in minfx https://gna.org/projects/minfx/, but this has not been implemented. Numerical gradients are hugely computationally expensive and can increase the computation time by an order of magnitude. Anyway, feel free to try to reintroduce the RelaxError if the Nelder-Mead simplex algorithm is not selected. _______________________________________________________ Reply to this item at: <http://gna.org/bugs/?22033> _______________________________________________ Message sent via/by Gna! http://gna.org/