Numerical Dirac Solver for Visualizations

Does anyone have the legacy code for numerically solving the 2+1D Dirac equation, using the fft approach or whatever Doran & Gull et al., did, to visualize the Stern-Gerlach filter streamlines.

I was wondering if anyone has a copy of that code, or even pseudo-code. I’d like to re-write it in Python and/or Mojo. I asked Chris Doran a while back, and he just mumbled something about using a FFT, but that was not helpful. I would not know how to start, and the one FFT based clifford numerical code in the published literature is a dogs body of C++ work, using particular code for the macroscopic field and boundary conditions that was next to impossible for me to decipher (Mocken and Keitel, 2008).