Hi,

I wanted to create a Y-shaped 3 terminal structure. For that, I declared 3 different type of lattices, namely lat_a,lat_b and lat_c.

Why do you have 3 different lattices? When I run your sample code I see that the 3 different lattices are actually the same. What are you trying to achieve? I would probably recommend using a single lattice and just cutting out the desired shape.

I am not able to declare hopping between lat_a,lat_b and lat_a,lat_c. Is there any way to declare hopping between two different type of lattices?

Of course you can declare hoppings between different types of lattices. In the sample code, when I uncomment line 38, I receive the following error and traceback: Traceback (most recent call last): File "sample.py", line 38, in <module> sys[lat_a(4, 4), lat_b(b_f-1, L)] = -t File "/home/jbw/.local/lib/python2.7/site-packages/kwant/builder.py", line 900, in __setitem__ func(sh, value) File "/home/jbw/.local/lib/python2.7/site-packages/kwant/builder.py", line 873, in _set_hopping b2 = b = self.H[b][0] KeyError: Site(kwant.lattice.Monatomic([[1.0, 1.0], [0.0, 1.0]], [0.0, 0.0], ''), array([-1, 20])) So we get a `KeyError` because the site mentioned does not exist in your system. If you look at the preceding lines in your script you will see that this is indeed the case: you never add site latb(-1, 20) to your system. Hope that helps, Joe