I implemented this in the streamline code already. To use it, set
"imomentum=1" in the setup file. Note that in this case we are not
solving for the velocity, but for the particle momentum,
p=gamma m v. That means we need to set the initial condition for p in
the data file via gendata.py. In these units, p=R_L (the Larmor
radius), so we would be setting the initial Larmor radius. Then there
is no need to use the parameter alpha!
Probably if you do it with slab, we will see the oscillations in the
diffusion coefficients occuring at time intervals of 1!