Dear all,

I am having a problem defining a system which matches what I want.

I start by defining a rectangular graphene lattice of size 0<=x<L in the x
direction and 0<=x<W in the y direction. (By "rectangular" I mean in the
real space coordinates, not the crystallographic coordinates.)

I want to attach a lead to the left-had end of this rectangle, going to
minus infinity. Therefore, I define a lead with translational symmetry
(-1,0) and the appropriate hopping. I attach the lead and plot the system.

When I plot the system, I find that the lead has been attached along the
(0,1) crystallographic direction (so, that is along the (1/2, sqrt(3)/3)
real space vector). A triangle of extra sites have been added for x<0 (real
space) so that the total shape of the scattering region is now not rectangular.

If I attach another lead with lead.reversed(), a similar thing happens on
the right of the sample so that my scattering region is now a parallelogram.

As I understand it, this should not affect the physics in any way, since the
lead is semi-infinite. But, if I want to draw pictures, plot functions over
the scattering region, and gain physical understanding, it is a bit of a
pain. So, my question is whether there is any way to make the lead attach
along the (0,1) real space direction (which is the same as the (-1,2)
crystallographic direction) and yet maintain the (-1,0) translational symmetry?

If you require a sample program which reproduces this behavior then I can
easily provide that, but I thought I should not extend an already long post

Thanks in advance.


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