EasySpin forum

Does it mean that J, eeD and dvec model (all together) will not work for two spins which are not identical (having dissimilar g tensors)? If so and then if I use Sys.ee, J_anisotropic would be Sigma Jij/3 but how can I calculate Jdip from Sys.ee 3X3 tensor ?

Well, I have mostly worked with the entire sys.ee because I like building the Hamiltonian by hand. The approach I described has worked pretty well in systems I had to treat.

However...

I guess you could use sys.eeD, if you properly define gFrame for your second spin (consider the first spin as a frame of reference). I haven't actually worked that way, so I cannot give more precise advice, but you could then avoid all those analytical expressions and be more free to define your g tensors. You would however have to work out how the Euler angles work for your system.