Hello everyone,

I want to compute and plot the current density in a graphene sample. I logically use kwant.operator.Current(syst) and then kwant.plotter.current(syst, current) to plot the current density in the sample.

However, the main example in the kwant documentation only uses the wavefunction associated to the first mode to compute J:

---

wf = kwant.wave_function(syst, energy=-0.3)

J0 = kwant.operator.Current(syst)

wf_left = wf(0)[0]

current = J0(wf_left)

---

In my case, I have a system with more than one mode. I have found some lines that consider all the modes (at the end of this page : https://kwant-project.org/doc/dev/tutorial/operators )

2.7. Computing local quantities: densities and currents ... kwant-project.org 2.7. Computing local quantities: densities and currents¶ In the previous tutorials we have mainly concentrated on calculating global properties such as conductance ...

 

---

wf_left = wf(0)

J_m_left = sum(J_m_bound(p) for p in wf_left)

J_z_left = sum(J_z_bound(p) for p in wf_left)

---

But this is equivalent to calculate the expression

which is simply the sum over the current coming from each mode. However, I would have rather use the following expression to find a more general expression of the current density

 

What is therefore the good way to find J? I have not found more informations in the Kwant documentation.

Best regards,

Nicolas