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FIG. 22: simplest_graphene example: the system monsys plotted with visu2D.
B. Solving
NOTE: With the lead solver than we are currently using, the hopping matrix t (from one layer to the
next of the lead) has to be invertible. There is no fundamental reason for that and this should be
fixed in later releases. As this matrix is not invertible for graphene we use a trick of adding a small
matrix to t (typically 1e-5 smaller than the bandwidth). The trick works well for medium size
systems but eventually become unstable.
Using KNIT, we calculate the conductance matrix for graphene ribbon and plot the result for
different energies.
MYDATA=[]
Ndata=101
for i in range(Ndata):
E= 3.5*((float(i)/Ndata)*2.-1.001)
G_MATRIX=obs.conductance_matrix(monsys,E)
MYDATA.append([E,G_MATRIX[0,1] ])
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