Hi Joe,
This is a nice hack! I once thought of a more systematic and cleaner
solution would be to produce the scattering matrix whose modes are
identical aside of spin degeneracy. This wouldn't rely on using the
slower and less stable Green's functions.
Forcing extra requirements on the modes in the lead is really quite
easy and can be preferable since you can probably save computational
costs also for the modes. For example in [1] we've done it for
time-reversal symmetry, and in [2] Michael used it to calculate
Andreev conductance in a neater way than what is suggested by the
Kwant tutorial.
I started implementing such leads once, but didn't have enough time to
come to a reasonable point.
Cheers,
Anton
[1]: http://arxiv.org/src/1408.1563v2/anc/trijunction.py (see class
TRIInfiniteSystem)
[2]: http://wwwhome.lorentz.leidenuniv.nl/~wimmer/tcscxviii/phlead.py
(was used for example in
http://nbviewer.ipython.org/url/wwwhome.lorentz.leidenuniv.nl/~wimmer/tcscxv...)
On Fri, Jul 17, 2015 at 7:44 PM, Joseph Weston
This time *with* the recipe attached
Joe