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.
I am using Kwant to study a system with both spins and electron and hole,
so the hopping matrix is 4X4. Now I want to know how to separate the spins,
electron and hole. I study this through the "2.6. Superconductors: orbital
degrees of freedom, conservation laws and symmetries"
smatrix = kwant.smatrix(syst, energy)
data.append(smatrix.submatrix((0, 0), (0, 0)).shape
-smatrix.transmission((0, 0), (0, 0)) +smatrix.transmission((0, 1), (0, 0)))
I do not find more information about this for kwant.
For my system, if I have 3 leads, and the hopping and onsite energy is set
in this order:
(e↑,0,0,0)- spin up electron,first row of the 4X4matrix
(0,e↓,0,0)- spin down electron,second row of the 4X4matrix
(0,0, h↑ ,0)- spin up hole,third row of the 4X4matrix
(0,0, 0, h ↓ )- spin down hole,fourth row of the 4X4matrix
I want to obtain the transmissions from 0 →2.
smatrix = kwant.smatrix(syst, energy)
The transmission from h↑ to e↑ is: smatrix.transmission((2, 1), (0, 2))
The transmission from h ↓ to e↑ is: smatrix.transmission((2, 1), (0, 3))
Is my understanding correct?
Thanks very much in advance!
We are organizing a 4 hour tutorial session where we will introduce the basic
concepts of quantum transport and how to use Kwant to make practical
calculations. This mini-workshop is aimed at experimental or theoretical
physicists who want to learn how to simulate coherent nanoelectronics devices
The hands-on sessions will cover several examples including graphene devices,
quantum Hall effect or devices with superconducting contacts.
The workshop will take place online on December 17th, 2020 from 15:00 to 19:00
CET (9:00 to 13:00 ET). More information and (free but mandatory) registration
can be found at https://virtualscienceforum.org/#/quantum-transport-workshop
We would be very grateful if you could forward this email to people potentially
interested in this tutorial. Also, we are putting together a team of people to
help supervising the hands-on sessions. Please join us if you can. You can
let us know that you're interested in helping us introduce new users to Kwant
by simply replying to this list (or drop us a note at
Anton, Christoph, Michael and Xavier
Answer below :
De : Christoph Groth <christoph.groth(a)cea.fr<mailto:email@example.com>> Envoyé : mercredi 25 novembre 2020 20:21 À : Olivier Leblanc <o.leblanc(a)uclouvain.be<mailto:firstname.lastname@example.org>> Cc : kwant-discuss(a)kwant-project.org<mailto:email@example.com> Objet : Re: [Kwant] tkwant issue solved
We are aware that tkwant is not available for Python 3.8 on conda-forge.
Unfortunately, as far as I understand, the underlying problem is beyond our control.
Olivier Leblanc wrote:
> My problem was that even when activating the virtual environment in
> cmd, launching "jupyter notebook" did not use the virtual environment
> because jupyter notebook was not part of it.
So, in other words, you installed tkwant in Python environment A and then you were surprised not to find it in Python environment B. Perhaps this can be seen as a design issue of Python virtual environments, or of Jupyter, but it's certainly not a problem specific to Tkwant or Kwant.
No, I installed tkwant in Python environment B, and launching jupyter notebook with environment B activated did not really use environment B but was keeping the environment A.
Thus tkwant was not found.
This is indeed a problem from python, but adding the last line I suggest wouldn't change anything for users that don't obtain the issue, and would solve the one I had because of Python and Jupyter notebook.
> Hoping this will be added on your website.
In my opinion listing possible generic problems that one may encounter when using Tkwant is beyond the scope of our web site. I think that this would render the instructions less useful by overloading them.
This means I do not ask you to make a generic problems listing, but simply add a command line in your installation tutorial.
I am a new PhD student at UCLouvain (Belgium).
Trying to install tkwant, I lost a lot of time with an issue I did not understand.
For windows users :
I suggest you to add "pip install jupyter"
conda create -n env-tkwant python=3.7
conda activate env-tkwant
conda install -c intel mpi4py
conda install tkwant -c conda-forge
pip install jupyter
My problem was that even when activating the virtual environment in cmd, launching "jupyter notebook" did not use the virtual environment because jupyter notebook was not part of it.
Thus the python version was kept to 3.8 (uncompatible with the current tkwant package), and I was receiving a "module not found error".
Hoping this will be added on your website.
Dear Kwant developers,
I was wondering if there were any examples of extracting the momenta of the
scattering states? I have found several functions in the documentation that
seem to cover what I would like to do, however, I have not managed to
implement them, unfortunately.
To be more specific, my problem is such that there are 'bands' in the left
lead, and I would like to see how many scattering states (+their momenta)
Kwant finds at a given value of the chemical potential in the lead.
Thank you in advance for your help!
I want to plot the the Charge density using kwant.plot method, I want to know how to plot the Charge density in a system with multiple orbitals per site.
Here is some pesuo codes:
syst = kwant.Builder()
(eigen,evecs) = la.eigh(ham)
return 2 * wf[i] / wf.max()
kwant.plot(model, site_size=site_size, site_color=(0, 0, 1, 0.3),fig_size=(10,10));
In my codes, I just found len(model.sites)=6, that is the number of sites in the unit cell, however, due to there are multiple orbitals per site, the len(evecs[:,i])=22 orbitals. So I want to know the real infortion when using kwant.plot? Like what I just posted, it only plot evecs[:6,i]**2 functions?
I want to draw a contour plot of the first Brillouin zone and band
structure along the path of high symmetry points by using Kwant. In Kwant,
I know that "kwant.wraparound.plot_2d_bands" function shows the Brillouin
zone in 3D. I read a kwant official documentary to find the information
that I want, but I couldn't find the solution.
My questions are as follows;
1) are there functions in kwant to draw 2D contour plot of the Brillouin
zone and the band structure along the path of high symmetry points?
2) If it is not, could I extract data shown from
Thank you for reading my email.
Department of Physics,
369, Sangdo-ro, Dongjak-gu,
Republic of Korea (South Korea)