Hi, thanks for the quick reply. Correct. I wanted to attach the lead at the center of the sample. The reason for inputting 13 < x < 15 is by an analogy with the first pair of leads (which were placed at the edges). On Tuesday, August 25, 2015 10:45 PM, Joseph Weston <joseph.weston08@gmail.com> wrote: Hi, Did you already do a search on the mailing list for calculating Hall conductance? I remember that a similar question has been asked before, and you may get a more comprehensive answer there.
How to attach another pair of leads at 13 < x < 15 and 23 < x < 25 with y = 10 and y =0?
I'm not entirely sure what you are trying to achieve; you seem to want a lead that is attached to the centre of the sample, but you are working with a 2D material. In any case, the shape function you posted
def lead2_shape(pos2): x, y = pos2 return 13 < x < 15, 10 < y < 10
cannot possibly work because: a) you return a tuple instead of a True or False value; b) even if the condition were `13 < x < 15 and 10 < y < 10`, this will always evaluate to False as `y` cannot be simultaneously less than and greater than 10. I would suggest that you define exactly what it is that you are trying to do, maybe posting a followup question to the mailing list
Also How to calculate hall conductance from these leads (assuming hopping is by Peierls substitution where t is replaced by an exponential)?
This is more of a physics question; I suggest you ask your professors about how to obtain the conductance matrix from the scattering matrix or else look online (maybe on https://physics.stackexchange.com/) or in a book. Happy kwanting, Joe