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?
TranslationalSymmetry does not work with my SimpleSite Family. Therefore, I attach the leads manually. I Use class kwant.builder.BuilderLead(builder, interface).
I define a builder in the following way:
#The tight-binding system of a left lead.
left_lead = kwant.Builder()
#Add sites lead
left_lead[lat(x1, y1)] = 1.5
left_lead[lat(x2, y2)] = 1.5
left_lead[lat(x2, y2), lat(x1, y1)] = 2j
The same way I define the interface(wich called left_sequence) but without the hoppings.
l_lead = kwant.builder.BuilderLead(left_lead, left_sequence).
But it does not work. Where I'm wrong?
As the lead I want to use the left and right boundary of my graphene atoms.
С уважением, Татьяна Григоренко
This question is basically the same as this: https://firstname.lastname@example.org/msg00076.html
I want to calculate some things using the scattering matrix. I started out with a very simple system, most basic two-terminal system. For some energy there is one propagating mode. I now add matrix structure to the mix (just multiply by s_0 everywhere) and there are now 2 propagating modes (which makes sense).
Now, if I look at the reflection coefficients for lead 0 by using submatrix(0,0), it is now a 2x2 matrix after I introduced the matrices. How are the elements ordered? Is it
[[r_upup, r_updown],[r_downup, r_downdown]]
I know that I could make two lattices, but since I do not plan to use the other functions such as transmission. I just want the smatrix.
Hope you can help me, and thanks in advance.
I am writing this to ask about how can I finalize the
sytem with translational invariance along two directions.
Code that I am using is the following as I want to make a slab system for
sym = kwant.TranslationalSymmetry([1, 0, 0], [0, 1, 0])
ValueError: Currently, only builders without or
with a 1D translational
symmetry can be finalized.
Is there any solution to this?
I also happen to get one code from notes on internet by
edx course where thwe following code has been used using wraparound function.
I did not get much out of it. Also, I checked I don't have this
function in my kwant module. how can I get this functions module?
Please anyone can explian what this function is doing in the code:
from functions import wraparound
syst = wraparound(bhz(Z=1, system_type='slab'))
syst = syst.finalized()
syst.leads = TRIInfiniteSystem(syst.leads, trs)
ANANT VIJAY VARMA
Great, thanks a lot!
On Mon, Jan 23, 2017 at 10:15 AM, Anton Akhmerov <
> > Thank you. Then to calculate the velocity, should I just divide the
> > probability current by the integral of |𝜓|2 over the unit cell?
> You could do that, but this is already done in Kwant, and you can read
> the velocities off from the modes object .
> : https://kwant-project.org/doc/1/reference/generated/kwant.
I was wondering what units would the wavefunction obtained from Kwant
have? I was thinking they would have the units 1/sqrt(nm.eV) (since my
energies are in eV and lengths are in nm) as the modes are normalized
[image: Inline image 1]
How would I calculate the velocity of the mode, if the modes are normalized
to carry unit current?
I used kwant to calculate the band structure of zigzag and armchair
graphene nanoribbons. For zigzag graphene nanoribbons, we have sym=
kwant.TranslationalSymmetry(lat.a.vec((-1, 0))). For armchair graphene
nanoribbons, we have sym= kwant.TranslationalSymmetry(lat.a.vec((-1, 2))).
My question is: which is the path in the Brillouin zone that we use and
label the x-axis accordingly? My figure is attached. Thanks in advance!
Не вопрос, напишу мануал.
On Tuesday, January 17, 2017 at 02:51 Anton Akhmerov <anton.akhmerov+kd(a)gmail.com> wrote:
Привет, можешь девушке помочь? (В смысле поделиться на нашем списке
рассылки как ты квант на WSL установл.)
---------- Forwarded message ----------
From: Anton Akhmerov
Date: Tue, Jan 17, 2017 at 10:48 AM
Subject: Re: [Kwant] Regarding smatrix and spin
To: Camilla Espedal
It seems that you are trying to install Kwant on windows. This is a
very hard task, and I fear none of the Kwant developers has enough
knowledge of it right now (our Windows packages are built by Christoph
Gohlke, see  for the build environment description). However if you
are using windows 10, I suggest to try to install Kwant using the
windows subsystem for linux. That way the standard Ubuntu build
procedure should work for you.
On Mon, Jan 16, 2017 at 9:45 AM, Camilla Espedal
> Thanks a lot. I tried to install the cons_laws_combined, but I get the following error message:
> "LINK: fatal error LNK1181: cannot open input file 'lapack.lib'"
> Is there some package or installation I am missing?
> Best regards,
> -----Original Message-----
> From: anton.akhmerov(a)gmail.com [mailto:email@example.com] On Behalf Of Anton Akhmerov
> Sent: 8. januar 2017 16:35
> To: Tómas Örn Rosdahl
> Cc: Camilla Espedal ; kwant-discuss(a)kwant-project.org
> Subject: Re: [Kwant] Regarding smatrix and spin
> Hi Camilla, everyone,
> I've slightly modified Tómas's example to a case where the spins do get coupled, check it out:
> I've also provided more detailed installation instructions in the notebook.
> On Sun, Jan 8, 2017 at 2:45 PM, Tómas Örn Rosdahl wrote:
>> Dear Camilla,
>> For a Hamiltonian with degeneracies due to a conservation law, the
>> scattering states will in general not have a definite value of the
>> conservation law. In your case, Kwant returns scattering states that
>> are arbitrary linear combinations of spin up and down, so it is not
>> possible to label the amplitudes in the scattering matrix by spin.
>> However, in Kwant 1.3 a feature will be added that allows for the
>> construction of scattering states with definite values of a
>> conservation law. See here for an explanation of the basic idea behind the algorithm.
>> We're currently working on implementing this feature in Kwant itself.
>> The good news is that we're practically done - here is a link to a git
>> repo with a functioning implementation. After you clone the repo,
>> check out the branch cons_laws_combined, which contains a version of
>> Kwant with conservation laws implemented. This notebook contains a
>> simple example to illustrate how to work with conservation laws and the scattering matrix.
>> I invite you and anyone else who is interested to give it a try. We'd
>> appreciate any feedback!
>> In your case specifically, there would be two projectors in the new
>> implementation - P0 which projects out the spin up block, and P1 that
>> projects out the spin down block. If they are specified in this order,
>> then the spin up and down blocks in the Hamiltonian have block indices
>> 0 and 1, respectively. In the new implementation, it is possible to
>> ask for subblocks of the scattering matrix relating not only any two
>> leads, but also any two conservation law blocks in any leads. To get
>> the reflection amplitude of an incident spin up electron from lead 0
>> into an outgoing spin down electron in lead 0, you could simply do
>> smat.submatrix((0, 1), (0, 0)). Here, the arguments are tuples of indices (lead index, block index).
>> Best regards,
>> On Fri, Jan 6, 2017 at 3:46 PM, Camilla Espedal
>>> Hi again,
>>> This question is basically the same as this:
>>> I want to calculate some things using the scattering matrix. I
>>> started out with a very simple system, most basic two-terminal
>>> system. For some energy there is one propagating mode. I now add
>>> matrix structure to the mix (just multiply by s_0 everywhere) and
>>> there are now 2 propagating modes (which makes sense).
>>> Now, if I look at the reflection coefficients for lead 0 by using
>>> submatrix(0,0), it is now a 2x2 matrix after I introduced the
>>> matrices. How are the elements ordered? Is it
>>> [[r_upup, r_updown],[r_downup, r_downdown]]
>>> I know that I could make two lattices, but since I do not plan to use
>>> the other functions such as transmission. I just want the smatrix.
>>> Hope you can help me, and thanks in advance.
>>> Best regards,