Dear All,
I have tried with a kwant code to see the transmission through barrier
imposed by a qwr between the
source and drain. The wire is constructed and its bands are formed
successfully; but the plot of
transmission through the constant barrier is not obtained. In the long run, I
would like to use the
standardised varying barrier potential and see the transport.
Please help me overcome this difficulty so that I may proceed further.
Kind regards.
K.K.Ghosh
PS. code is attached herewith.
import kwant
import numpy as np
from matplotlib import pyplot
lat=kwant.lattice.square()
def lead_0(W=10,t=1):
lead=kwant.Builder(kwant.TranslationalSymmetry([-1,0]))
lead[(lat(0,y) for y in range(W))]=4*t
lead[lat.neighbors()]=-t
return lead
def qwr_with_barrier(W=10,L=5,t=1):
def onsite_pot(s,v):
(x,y)=s.pos
return (4-v)*t
qwr=kwant.Builder()
qwr[(lat(x,y) for x in range(L) for y in range(W))]=onsite_pot
qwr[lat.neighbors()]=-t
lead=lead_0()
qwr.attach_lead(lead)
qwr.attach_lead(lead.reversed())
return qwr
def plot_transmission(lead,energy,params):
trans=[]
for param in params:
smatrix=kwant.smatrix(lead,energy,args=[param])
trans.append(smatrix,transmission(1,0))
pyplot.plot(params,trans)
pyplot.show()
def main():
_syst=qwr_with_barrier()
kwant.plot(_syst)
_syst=_syst.finalized()
kwant.plotter.bands(_syst.leads[0])
if __name__=='__main__':
main()
