I am a PhD student of Hong Kong University of Science and Technology. I
want to use KWANT to caculate Hall resistance of a Hall bar structure.We
can get the conductance between 6 electrodes, but how to get hall
resistance? Can you give me some help? Thank you very much.
Hello Kwant experts,
I have studied Kwant a bit, but before I delve deeper into it, I want to
know if it can be applied to my problem.
I have a 3d electron potential landscape for a metal-vacuum surface
calculated with DFT. (More detailed info and pictures in ). Can I use
Kwant to calculate the transmission probability of electrons incident on
And if kwant is not suitable for this problem, perhaps you know of any
other numerical software or method that would allow this calculation?
This question is sort of related to one of mye previous questions (https://firstname.lastname@example.org/msg01029.html) but I am writing it as a new one. The questions relates to the sites in the lead unit cell and the scattering matrix.
Say I have a system (simple 2D wire), where I have 3 sites in my unit cell (3 orbitals). I then make a system at an energy which is so low that I only have one propagating mode in the system. If I then run
it returns a 2x3 matrix (which corresponds to left/right going and number of orbitals). If I then run
I only get one element, which orbital does this element "belong" to, or how does it relate to these orbitals? Is the scattering matrix the same for all orbitals? Is the probability of scattering from say orbital 1 in one lead to orbital 2 in another the same as from orbital 1 to orbital 1?
Hope my question makes sens.
If I calculate the Rashba term, (S \times d_ij)_z, for one case the
Sigma_X terms comes out (in KWANT along (0,0) direction). That's why I
have included this term in my system. There is no other reason.
It feels that there may be something wrong in my calculation since you
have said about the Sigma_z conservation.
Can I show you my calculations. It'll not take much time, there are only
Hope you don't mind.
> Dear Sudin,
> 1. I mean the conservation of sigma_z.
> 2. There is no motivation for it, that's just what you have done in your
> On Wed, Nov 23, 2016 at 10:44 PM, Sudin Ganguly <sudin(a)iitg.ernet.in>
>> Dear Sir,
>> First of all, I would like to apologize in advance, if this mail bothers
>> Today you send me reply about the smatrix for up and down spins in
>> That was very much helpful to me.
>> I would like to ask you about the conservation law in the leads, since
>> does not seem right to post this kind of question in KWANT forum.
>> 1. is this Conservation law meant the current conservation? If this is
>> how do I understand this.
>> 2. Kane-Mele model said that in graphene there is NN Rashba interaction,
>> and other is NNN intrinsic SO interaction. Then what is the motivation
>> avoid these kind of interactions in the leads.
>> I'll be eagerly waiting for your reply.
>> With Regards,
>> Sudin Ganguly
>> Research Scholar
>> Dept. of Physics
>> IIT Guwahati
I'm trying to get the transmission coefficients for up and down spin
channels in graphene with Kane-Mele Hamiltonian (including Rashba term).
So it needs to write the Hamiltonian for up and down spin separately.
I started with this,
My confusion is that, can I declare these sublattices for up and down spins.
I have a question regarding the lead_info[x].wave_functions[x]. I am not sure what this is actually returning? I tried to run the function on your quantum_wire_revisited.py-system, like this
prop = sm.lead_info
with W = 2, if that is important. It then returns a 1x2 array or 2x2 matrix depending on the energy. What does this matrix contain? I read about propagatingmodes in the documentation, but I am not sure what it meant.
So here is what I want to do. I have a system where I have defined two lattices, lat_up and lat_down, and they overlap spatially (instead of using matrices in the voltage and hopping, so that it is easier to obtain spin-resolved data). They are defined like this:
lat_up = kwant.lattice.general([(a,a),(a,-a)],[(0,0),(a,0)], name='up')
A_up, B_up = lat_up.sublattices
lat_down = kwant.lattice.general([(a,a),(a,-a)],[(0+d,0),(a+d,0+d)], name='down')
A_down, B_down = lat_down.sublattices
I want to calculate the trace of the dot product between sigma_z and the spinor psi = (psi_up psi_down), and plot it over the system. That is H(lat_up(i,i)) - H(lat_down(i,i)).
This was easy to do, when I used matrices for spin, but now that I have implemented it using two lattices instead I don't know how to do it. If I use the same approach as before, I get two values for each (spatial) lattice point, and the result looks completely random.
I hope my explanation was understandable.