Dear Joseph Weston

Thank you very much for your quick response. Of course, I can post you my cod example. It is in the following:

import kwant import matplotlib.pyplot as plt import math

d=1.42; a1=d*math.sqrt(3); t=-0.033;

latt = kwant.lattice.general([(a1,0),(a1*0.5,a1*math.sqrt(3)/2)], [(a1/2,-d/2),(a1/2,d/2)]) a,b = latt.sublattices syst= kwant.Builder()

#................................................................................... def rectangle(pos): x, y = pos z=x**2+y**2 return -4.75*a1<x<4.75*a1 and -8*d<y<8*d

syst[latt.shape(rectangle, (1,1))]=0

def delet(pos): x, y = pos z=x**2+y**2 return z<(1*a1)**2

del syst[latt.shape(delet, (1,1))]

#nearest neighbors............................................................. syst[[kwant.builder.HoppingKind((0,0),a,b)]] =t syst[[kwant.builder.HoppingKind((0,1),a,b)]] =t syst[[kwant.builder.HoppingKind((-1,1),a,b)]] =t

sym = kwant.TranslationalSymmetry(latt.vec((-4,0)))

sym.add_site_family(latt.sublattices[0], other_vectors=[(-1, 2)]) sym.add_site_family(latt.sublattices[1], other_vectors=[(-1, 2)]) lead = kwant.Builder(sym)

def lead_shape(pos): x, y = pos return -8*d<y<8*d

lead[latt.shape(lead_shape, (1,1))] = 0

def delet_lead(pos): x, y = pos z=x**2+y**2 return z<(1*a1)**2

del lead[latt.shape(delet_lead, (1,1))]

lead[[kwant.builder.HoppingKind((0,0),a,b)]] =t lead[[kwant.builder.HoppingKind((0,1),a,b)]] =t lead[[kwant.builder.HoppingKind((-1,1),a,b)]] =t

syst.attach_lead(lead,add_cells=3) syst.attach_lead(lead.reversed(),add_cells=3)

ax=kwant.plot(syst);

Best wishes, Nafise