Hey Bruce,
thanks for your fast answer! I just uploaded my complete notebook file.
Best regards, Philipp
thanks for looking it up. I just uploaded the nb.
Best regards, Pantelis
philipp, The NMinimize:ivar warning appears to say that k (kappa) has a value and should not be used as an independent variable in NMinimize.
Both: attaching a notebook file with your code would make it easier for others to try to help.