EasySpin forum

I am using pepper to simulate the spectrum of an Mn(II) impurity in calcium carbonate. I can do a good job at 9.5 GHz but can not come close at low fields (300 MHz). I suspect it is looping transitions. Is there any way to eliminate or minimize this problem?

If you have looping transitions, first make sure that you use matrix diagonalization and not perturbation theory (see Opt.Method. Also, for a powder simulation with looping transitions you might need to substantially increase the number of orientations (see Opt.nKnots).