I'm trying out Kwant, and I've encountered a problem when investigating 1D leads.
The simplest minimal example would be to take your file "quantum_wire_revisited.py", set W=1 there, and change the energy window to
energies=[0.01 * i for i in xrange(1000)]
The lattice is plotted correctly, but the conductance calculation yields a "ValueError: expected square matrix".
Changing "kwant.lattice.square" to "kwant.lattice.chain" does not solve the problem. Can you reproduce the error, or could there be a problem with my Kwant installation?