Dear Sir,
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.
Best Regards,
Zhang Bing

Well i am trying this paper:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.95.226801
I have one more thing to ask,that in the kwant paper the topological
suerconductor example is given.I have seen its band sturcture.How can one
say that it is a topological in nature,as its its band stucture overlaps on
increasing the onsite values more and more. I mean I am trying same for 2
dimension and as i increse its size or onsite potential the bands overlaps
more and more.Which confuses me with this , that whether it is topological
insulator or not,I guess that example sincerely means to represent edge
states only .Could you guide me doing the same thing for 2 d.?
ANANT VIJAY VARMA
M.Tech. STUDENT
CENTER FOR CONVERGING TECHNOLOGIES
UNIVERSITY OF RAJASTHAN
JAIPUR
On Sun, Nov 23, 2014 at 5:32 PM, <kwant-discuss-request(a)kwant-project.org>
wrote:
> Send Kwant-discuss mailing list submissions to
> kwant-discuss(a)kwant-project.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://mailman-mail5.webfaction.com/listinfo/kwant-discuss
> or, via email, send a message with subject or body 'help' to
> kwant-discuss-request(a)kwant-project.org
>
> You can reach the person managing the list at
> kwant-discuss-owner(a)kwant-project.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Kwant-discuss digest..."
>
>
> Today's Topics:
>
> 1. About kane and mele model like crossover (ANANT)
> 2. Re: About kane and mele model like crossover (Robert Sokolewicz)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 22 Nov 2014 12:27:35 +0000 (UTC)
> From: ANANT <avterminator(a)gmail.com>
> To: kwant-discuss(a)kwant-project.org
> Subject: [Kwant] About kane and mele model like crossover
> Message-ID: <loom.20141122T132433-754(a)post.gmane.org>
> Content-Type: text/plain; charset=us-ascii
>
> hello everyone,
> I am trying to simulate the Kane and mele like crossover of bands in Zigzag
> geometry.
> But my bans are not spillting or not I dont get.Bcoz bandstructure show
> that
> they are overlapping at all,as shown by colors.Here is my code.
> # -*- coding: utf-8 -*-
> # <nbformat>3.0</nbformat>
>
> # <codecell>
>
> #required files are imported
> import kwant
> import matplotlib.pyplot
> import math
> import numpy as np
> from cmath import exp
> import tinyarray
>
> # <codecell>
>
> #lattice defined A,B are sublattices.
> lat = kwant.lattice.general([(2.46,0), (1.23,1.23*math.sqrt(3))],[(0,0),
> (0,2.46/ math.sqrt(3))])
> A,B= lat.sublattices
> # All pauli matrices to define spin degree of freedom.
> s_0=np.identity(2)
> s_z =np.array([[1, 0], [0, -1]])
> s_x = np.array([[0, 1], [1, 0]])
> s_y = np.array([[0, -1j], [1j, 0]])
>
> for x in xrange(1):
> def make(a=50,b=11,t=1,alpha =.09):
> sym0 = kwant.TranslationalSymmetry(lat.vec((-1,0)))
> #system building
> def shape(pos):
> x, y = pos
> return (0<= y <=b)
> sys = kwant.Builder(sym0)
> #onsite enegies
> for j in range(b):
> sys[A(0,j+1)] =.1*s_0
> sys[B(0,j)] = -.1*s_0
> sys[kwant.builder.HoppingKind((0, 0), A,B )]= - t *s_0 + 1j * alpha
> *s_z # hopping in y direction
> sys[kwant.builder.HoppingKind((-1,1), A,B )] =-t *s_0 - 1j * alpha
> *s_x# hopping in x direction
> sys[kwant.builder.HoppingKind((0,1), A,B )] = -t *s_0 + 1j * alpha
> *s_y# hopping in x direction
> #sys[lat.neighbors()]= -t
> #sys[lat.neighbors()]= -2.6*s_z
> return sys
> #main() function call
> def main():
> sys= make().finalized()
> #plotting a band structure
> kwant.plotter.bands(sys,momenta= np.linspace(-5,5,1000),show =
> False)
> matplotlib.pyplot.xlabel("S_momentum")
> matplotlib.pyplot.ylabel("S_energy [t]")
> matplotlib.pyplot.show()
> if __name__ == '__main__':
> main()
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 22 Nov 2014 20:32:28 +0100
> From: Robert Sokolewicz <r.sokolewicz(a)gmail.com>
> To: ANANT <avterminator(a)gmail.com>
> Cc: kwant-discuss(a)kwant-project.org
> Subject: Re: [Kwant] About kane and mele model like crossover
> Message-ID:
> <CAP+R9snmUJ-MhxbpQ4J9827RtJ_fMj7fommU=+
> vFwih6otV+qQ(a)mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> hi Anant,
>
> could you explain in a bit more detail what you are trying to accomplish?
> which model are you using specifically? Perhaps you made a mistake
> implementing the tight binding hamiltonian?
>
> cheers,
> Robert
>
> On Sat, Nov 22, 2014 at 1:27 PM, ANANT <avterminator(a)gmail.com> wrote:
>
> > hello everyone,
> > I am trying to simulate the Kane and mele like crossover of bands in
> Zigzag
> > geometry.
> > But my bans are not spillting or not I dont get.Bcoz bandstructure show
> > that
> > they are overlapping at all,as shown by colors.Here is my code.
> > # -*- coding: utf-8 -*-
> > # <nbformat>3.0</nbformat>
> >
> > # <codecell>
> >
> > #required files are imported
> > import kwant
> > import matplotlib.pyplot
> > import math
> > import numpy as np
> > from cmath import exp
> > import tinyarray
> >
> > # <codecell>
> >
> > #lattice defined A,B are sublattices.
> > lat = kwant.lattice.general([(2.46,0), (1.23,1.23*math.sqrt(3))],[(0,0),
> > (0,2.46/ math.sqrt(3))])
> > A,B= lat.sublattices
> > # All pauli matrices to define spin degree of freedom.
> > s_0=np.identity(2)
> > s_z =np.array([[1, 0], [0, -1]])
> > s_x = np.array([[0, 1], [1, 0]])
> > s_y = np.array([[0, -1j], [1j, 0]])
> >
> > for x in xrange(1):
> > def make(a=50,b=11,t=1,alpha =.09):
> > sym0 = kwant.TranslationalSymmetry(lat.vec((-1,0)))
> > #system building
> > def shape(pos):
> > x, y = pos
> > return (0<= y <=b)
> > sys = kwant.Builder(sym0)
> > #onsite enegies
> > for j in range(b):
> > sys[A(0,j+1)] =.1*s_0
> > sys[B(0,j)] = -.1*s_0
> > sys[kwant.builder.HoppingKind((0, 0), A,B )]= - t *s_0 + 1j *
> alpha
> > *s_z # hopping in y direction
> > sys[kwant.builder.HoppingKind((-1,1), A,B )] =-t *s_0 - 1j *
> alpha
> > *s_x# hopping in x direction
> > sys[kwant.builder.HoppingKind((0,1), A,B )] = -t *s_0 + 1j *
> alpha
> > *s_y# hopping in x direction
> > #sys[lat.neighbors()]= -t
> > #sys[lat.neighbors()]= -2.6*s_z
> > return sys
> > #main() function call
> > def main():
> > sys= make().finalized()
> > #plotting a band structure
> > kwant.plotter.bands(sys,momenta= np.linspace(-5,5,1000),show =
> > False)
> > matplotlib.pyplot.xlabel("S_momentum")
> > matplotlib.pyplot.ylabel("S_energy [t]")
> > matplotlib.pyplot.show()
> > if __name__ == '__main__':
> > main()
> >
> >
> >
> >
>

hello everyone,
I am trying to simulate the Kane and mele like crossover of bands in Zigzag
geometry.
But my bans are not spillting or not I dont get.Bcoz bandstructure show that
they are overlapping at all,as shown by colors.Here is my code.
# -*- coding: utf-8 -*-
# <nbformat>3.0</nbformat>
# <codecell>
#required files are imported
import kwant
import matplotlib.pyplot
import math
import numpy as np
from cmath import exp
import tinyarray
# <codecell>
#lattice defined A,B are sublattices.
lat = kwant.lattice.general([(2.46,0), (1.23,1.23*math.sqrt(3))],[(0,0),
(0,2.46/ math.sqrt(3))])
A,B= lat.sublattices
# All pauli matrices to define spin degree of freedom.
s_0=np.identity(2)
s_z =np.array([[1, 0], [0, -1]])
s_x = np.array([[0, 1], [1, 0]])
s_y = np.array([[0, -1j], [1j, 0]])
for x in xrange(1):
def make(a=50,b=11,t=1,alpha =.09):
sym0 = kwant.TranslationalSymmetry(lat.vec((-1,0)))
#system building
def shape(pos):
x, y = pos
return (0<= y <=b)
sys = kwant.Builder(sym0)
#onsite enegies
for j in range(b):
sys[A(0,j+1)] =.1*s_0
sys[B(0,j)] = -.1*s_0
sys[kwant.builder.HoppingKind((0, 0), A,B )]= - t *s_0 + 1j * alpha
*s_z # hopping in y direction
sys[kwant.builder.HoppingKind((-1,1), A,B )] =-t *s_0 - 1j * alpha
*s_x# hopping in x direction
sys[kwant.builder.HoppingKind((0,1), A,B )] = -t *s_0 + 1j * alpha
*s_y# hopping in x direction
#sys[lat.neighbors()]= -t
#sys[lat.neighbors()]= -2.6*s_z
return sys
#main() function call
def main():
sys= make().finalized()
#plotting a band structure
kwant.plotter.bands(sys,momenta= np.linspace(-5,5,1000),show = False)
matplotlib.pyplot.xlabel("S_momentum")
matplotlib.pyplot.ylabel("S_energy [t]")
matplotlib.pyplot.show()
if __name__ == '__main__':
main()

hello everyone.
I am not getting eigenfunction plot of a chain lattice.
Showing some bug.Please tell me what is wrong with my code:
import kwant
from cmath import exp
import matplotlib.pyplot
import tinyarray
import numpy as np
import scipy.sparse.linalg as sla
lat = kwant.lattice.general([(1,0),(0,1)],[(0,0),(0,1)])
A,B = lat.sublattices
s_0 = np.identity(2)
s_z =np.array([[1, 0], [0, -1]])
s_x = np.array([[0, 1], [1, 0]])
s_y = np.array([[0, -1j], [1j, 0]])
def make(a=10,b=1,t=1,delta=.00,mu=.0):
def Square(pos):
x , y = pos
return 0<=x<=a and 0<=y<=b
sys = kwant.Builder()
sys[lat.shape(Square,(0,0))] = -mu*s_0
sys[lat.neighbors()] = -t*s_0 + delta*s_x
return sys
def plot_wave_function(sys):
# Calculate the wave functions in the system.
ham_mat = sys.hamiltonian_submatrix(sparse=True)
evecs = sla.eigsh(ham_mat, k=12)[1]
# Plot the probability density of the 10th eigenmode.
kwant.plotter.map(sys, np.abs(evecs[:, 7])**2,colorbar=True,
oversampling=10)
def main():
sys = make()
kwant.plot(sys)
sys = sys.finalized()
plot_wave_function(sys)
if __name__ == '__main__':
main()
this code is showing following error:
OverflowError: cannot convert float infinity to integer

Hi Michael,
Thanks for getting back to me. Sorry for the delay in getting back to you
too.
each of your lattice points will correspond to a finite volume in real-space
> (for example, in a cubic lattice with lattice constant a this volume
> would be a^3).
Neat; that clarifies a lot of things.
It turns out that a student of ours is also working on combining kwant with
> the Poisson equation! Out of curiosity: What is your experience with
> FiPy? Can you recommend using it?
>
FiPy's solvers perform well, and it's easy to set up on windows and linux
(I haven't tried OSX), but the documentation isn't great and it has trouble
with complex boundary conditions (particularly internal
boundary conditions; look elsewhere if you want to fix internal values
easily and reliably). Some other technical and specific things: I had to
download the dev version and tinker with the source a bit to get certain
kinds of periodic 3d boundary conditions working, but those changes should
all be in the dev branch now; sampling from FiPy grids (even uniform grids)
can be very slow unless you pre-compute the nearest cells to your sampling
points (the default behaviour does an O(n) lookup to find the nearest cell
to every point you want to sample from).
I've got some decent code for interfacing between kwant and FiPy in 2D
(with matching square lattices), and some uglier code for arbitrary 3D
lattices; I'll put it up on github and send you the link in a week or so.
Regards,
Daniel R-P
On 25 October 2014 09:27, Michael Wimmer <wimmer(a)lorentz.leidenuniv.nl>
wrote:
> Dear Daniel,
>
> sorry for the long delay - I started to work on a reply before
> traveling, and then it took some time to get back to your question.
>
> First, with regards to your units question: When you write down the
> Hamiltonian in kwant (in kwant, we just have numbers), you choose a unit
> of energy (e.g. if all matrix elements are in meV, this unit is meV).
> Also, each of your lattice points will correspond to a finite volume in
> real-space (for example, in a cubic lattice with lattice constant a this
> volume would be a^3).
>
> All the functions in kwant will reflect these units. For example, the
> local density of states (LDOS) has units per energy per volume. Kwant's
> ldos thus returns for every site the number of electrons per chosen unit
> of energy per lattice point volume.
>
> This units are fixed and do not depend on system size. Hence, when you
> integrate ldos over space to get the total DOS D(E), D(E) will indeed
> scale with system size, as you expected. I include a little example
> below where this is demonstrated. If you do not observe this for your
> model, I believe this means your model is not correct.
>
> You correctly assume that ldos is essentially a sum over all incoming
> scattering wave functions (and divided by 2 pi). One can show that this
> is equivalent to the Green's function expression. This also indicates
> how you can compute the ldos in the infinite lead, namely by summing
> over all propagating modes and dividing by 2 pi. Alternatively, one can
> just make a scattering system that is equivalent to an infinite system.
> I compare both approaches in an example below.
>
> I suppose that for your problem you rather need the ldos integrated over
> energy rather than integrated over space right? The former will give you
> charge density.
>
> It turns out that a student of ours is also working on combining kwant
> with the Poisson equation! Out of curiosity: What is your experience
> with FiPy? Can you recommend using it?
>
> Best regards,
>
> Michael
>
> ================================================
> Program codes
> ================================================
> # Example: scaling of DOS with system size
>
> import kwant
> import numpy as np
>
> def dos(energy, L):
> lat = kwant.lattice.chain()
> sys = kwant.Builder()
>
> for x in xrange(L):
> sys[lat(x)] = 2
> sys[lat.neighbors()] = -1
>
> lead = kwant.Builder(kwant.TranslationalSymmetry((-1,)))
> lead[lat(0)] = 2
> lead[lat.neighbors()] = -1
>
> sys.attach_lead(lead)
> sys.attach_lead(lead.reversed())
>
> sys = sys.finalized()
>
> return np.sum(kwant.ldos(sys, energy))
>
> import matplotlib.pyplot as plt
>
> L_arr = range(1, 20)
> dos_arr = []
>
> for L in xrange(1, 20):
> dos_arr.append(dos(0.3, L))
>
> plt.plot(L_arr, dos_arr)
> plt.show()
>
> =======================================================
> # Example: ldos of infinite system
>
> import kwant
>
> import numpy as np
> import matplotlib.pyplot as plt
>
> W = 30
> lat = kwant.lattice.square()
>
> sys = kwant.Builder()
> for y in xrange(W):
> sys[lat(0, y)] = 4
> sys[lat.neighbors()] = -1
>
> lead = kwant.Builder(kwant.TranslationalSymmetry((-1, 0)))
> for y in xrange(W):
> lead[lat(0, y)] = 4
> lead[lat.neighbors()] = -1
>
> sys.attach_lead(lead)
> sys.attach_lead(lead.reversed())
>
> sys = sys.finalized()
>
> # Compute ldos in scattering region
> # (since system is completely translationally
> # invariant, this is equivalent to an infinite
> # system)
> sys_ldos = kwant.ldos(sys, energy=0.6)
> y_arr = []
> for i in xrange(sys.graph.num_nodes):
> y_arr.append(sys.site(i).pos[1])
> y_arr = np.asarray(y_arr)
> indx = np.argsort(y_arr)
>
> # Compute ldos of infinite system directly
>
> def lead_ldos(lead, energy):
> prop_modes = lead.modes(energy=energy)[0]
>
> ldos = np.zeros((prop_modes.wave_functions.shape[0],), float)
> for i in xrange(prop_modes.wave_functions.shape[1]):
> ldos += abs(prop_modes.wave_functions[:, i])**2
>
> return ldos/2.0/np.pi
>
> l_ldos = lead_ldos(sys.leads[0], energy=0.6)
> yl_arr = []
> for i in xrange(sys.leads[0].cell_size):
> yl_arr.append(sys.leads[0].site(i).pos[1])
> yl_arr = np.asarray(yl_arr)
> lindx = np.argsort(yl_arr)
>
> plt.plot(y_arr[indx], sys_ldos[indx])
> plt.plot(yl_arr[lindx], l_ldos[lindx], 'o')
> plt.show()
>
>
> On 13.09.2014 17:14, Daniel Rodgers-Pryor wrote:
> > Hi,
> >
> > Firstly, thanks for creating Kwant - it's so nice to use physics code
> > written by people who understand software-engineering as well as physics
> :)
> >
> > I've got a few questions about units and density-of-states in Kwant,
> > please respond if you know anything about any of them; don't feel the
> > need to respond to them all at once.
> >
> > I'm trying to add self-consistent electrostatics to my Kwant system
> > (using FiPy as a finite-element/volume Poisson-solver). Obviously, I
> > need to calculate the electron-carrier-density of the system by
> > integrating over the Fermi-Dirac occupation, then feed that (via
> > real-space basis functions) to my Poisson solver. I'm not quite sure how
> > to handle the density of states in the context of Kwant:
> >
> > I assume that just summing over the LDOS (integrating over all space)
> > will give the density of states as a function of energy, D(E). Plotting
> > it seems to produce reasonable bands, but I'm not quite sure about the
> > units, or how it scales with system size. In the system I'm modelling
> > (low-temperature p-donors in silicon), every lattice site adds an
> > electron to the system (the temperatures are low enough that the silicon
> > is frozen-out as a conductor and can just be treated as a background
> > dielectric constant). I should be able to integrate over the
> > density-of-states until the total equals the (known) number of
> > electrons, but the density of states obtained by summing over the LDOS
> > calculated by Kwant does not scale properly with the number of sites in
> > the system; larger systems always need higher Fermi energies, which
> > isn't physical at all.
> >
> > What am I missing here? Are the units of the LDOS Kwant calculates
> > somehow normalised? How can I get a density-of-states which scales
> > appropriately with the total number of electrons/sites in my system?
> >
> > The lead unit-cell of my system will need to be solved self-consistently
> > too; how can I calculate the local density of states (and thus, via
> > Fermi-Dirac, the electron-density) of a lead?
> >
> > Am I correct in assuming that the LDOS produced by Kwant is equivalent
> > to summing over the state-density-weighted scattering-wavefunctions from
> > the modes in all leads (and thus that integrating it over the
> > occupied-energies will produce a sensible total electron-density)?
> >
> > Finally, and slightly unrelated, do my chosen energy-units need to be
> > accounted-for anywhere in Kwant's Schroedinger-solutions? I'm writing my
> > Hamiltonian terms in meV; will bands, LDOS etc. all naturally scale to
> > make this choice transparent? Similarly, does effective electron-mass
> > need to be accounted for at all?
> >
> > Thanks so much for your help,
> >
> > Daniel R-P
>

Dear Mac users,
the Mac installation of kwant should now work again with both package
managers (macports and homebrew):
* we have fixed the previous problems with macports. This should work again.
* we have updated the installation instructions for homebrew. If you had
problems with that package manager before, please try using the new
instructions.
If there are any problems remaining, please notify us (over this mailing
list). We have a working Mac again (the Mac we used to test the
installation was broken and took more than two months to get repaired)
and future issues should be resolved much faster.
In addition, we have also updated kwant in both package managers to the
current version 1.0.2 that solves an earlier issue with matplotlib
version 1.4.0 or newer.
All the best,
Michael

hello joe,
yes you are right it is more of fizics question....I will following the
same you said ...next time,But thank you so much for helping me anyways.
ANANT VIJAY VARMA
M.Tech. STUDENT
CENTER FOR CONVERGING TECHNOLOGIES
UNIVERSITY OF RAJASTHAN
JAIPUR
On Mon, Nov 10, 2014 at 5:33 PM, <kwant-discuss-request(a)kwant-project.org>
wrote:
> Send Kwant-discuss mailing list submissions to
> kwant-discuss(a)kwant-project.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://mailman-mail5.webfaction.com/listinfo/kwant-discuss
> or, via email, send a message with subject or body 'help' to
> kwant-discuss-request(a)kwant-project.org
>
> You can reach the person managing the list at
> kwant-discuss-owner(a)kwant-project.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Kwant-discuss digest..."
>
>
> Today's Topics:
>
> 1. Re: Kwant-discuss Digest, Vol 15, Issue 2 (ANANT VIJAY)
> 2. Re: About spin orbital coupling (Joseph Weston)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 10 Nov 2014 12:02:21 +0530
> From: ANANT VIJAY <anantvijaycct(a)gmail.com>
> To: kwant-discuss(a)kwant-project.org
> Subject: Re: [Kwant] Kwant-discuss Digest, Vol 15, Issue 2
> Message-ID:
> <CAN8vUmXQR=0AW0J87=
> tM6hAdWgf5_H1ut4u+HQeAGC0hGHkPBg(a)mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> well i am trying to generate the spin orbital coupling in the graphne
> lattice...or I should say I am looking for Quantum spin hall effect .Here i
> am using 2x2 matrix.I am not very sure about this also.As gien in tutorial
> SOI is -i*alpha(delx*sigma_y-dely*sigma_x),which gives me hopping in x and
> y diretions respectively.Here in graphene lattice the hopping is 3
> different directions as i mentioned in last post .and i want to write hop
> for these .Do I need to take the sin cos component of above expression or
> what ?
> please help.thank you
>
>
> ANANT VIJAY VARMA
> M.Tech. STUDENT
> CENTER FOR CONVERGING TECHNOLOGIES
> UNIVERSITY OF RAJASTHAN
> JAIPUR
>
> On Fri, Nov 7, 2014 at 5:33 PM, <kwant-discuss-request(a)kwant-project.org>
> wrote:
>
> > Send Kwant-discuss mailing list submissions to
> > kwant-discuss(a)kwant-project.org
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > https://mailman-mail5.webfaction.com/listinfo/kwant-discuss
> > or, via email, send a message with subject or body 'help' to
> > kwant-discuss-request(a)kwant-project.org
> >
> > You can reach the person managing the list at
> > kwant-discuss-owner(a)kwant-project.org
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of Kwant-discuss digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Re: About spin orbital coupling (Joseph Weston)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Thu, 06 Nov 2014 14:08:24 +0100
> > From: Joseph Weston <joseph.weston(a)cea.fr>
> > To: kwant-discuss(a)kwant-project.org
> > Subject: Re: [Kwant] About spin orbital coupling
> > Message-ID: <545B72C8.8060103(a)cea.fr>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > On 06/11/14 08:45, ANANT wrote:
> > > Hello everyone. I am applying the spin orbit coupling to the honeycomb
> > > lattice but there are three different kind of hopping and I am writing
> > this
> > >
> > >
> > > sys[lat.shape(shape, (2.46, 0))] =onsite
> > > sys[kwant.builder.HoppingKind((0, 0), A,B )]= -t * s_0 - 1j * alpha *
> s_y
> > >
> > > sys[kwant.builder.HoppingKind((0,1), A,B )] = -t * s_0 + 1j * alpha *
> s_x
> > >
> > > sys[kwant.builder.HoppingKind((-1,1), A,B )] = -t * s_0 + 1j * alpha *
> > s_x
> > >
> > > But this is not right .What should I write in place of this.? please
> > help me
> > > thank yo u in advance
> >
> > Hello,
> >
> > Can you be a bit more specific about what it is that you are doing:
> > - what model are you are using for spin orbit?
> > - what is the expected output?
> > - what is the actual output?
> >
> > It is always useful to be as specific as possible, especially through
> > the medium of email.
> >
> > Thanks,
> >
> > Joe
> >
> >
> >
> >

well i am trying to generate the spin orbital coupling in the graphne
lattice...or I should say I am looking for Quantum spin hall effect .Here i
am using 2x2 matrix.I am not very sure about this also.As gien in tutorial
SOI is -i*alpha(delx*sigma_y-dely*sigma_x),which gives me hopping in x and
y diretions respectively.Here in graphene lattice the hopping is 3
different directions as i mentioned in last post .and i want to write hop
for these .Do I need to take the sin cos component of above expression or
what ?
please help.thank you
ANANT VIJAY VARMA
M.Tech. STUDENT
CENTER FOR CONVERGING TECHNOLOGIES
UNIVERSITY OF RAJASTHAN
JAIPUR
On Fri, Nov 7, 2014 at 5:33 PM, <kwant-discuss-request(a)kwant-project.org>
wrote:
> Send Kwant-discuss mailing list submissions to
> kwant-discuss(a)kwant-project.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://mailman-mail5.webfaction.com/listinfo/kwant-discuss
> or, via email, send a message with subject or body 'help' to
> kwant-discuss-request(a)kwant-project.org
>
> You can reach the person managing the list at
> kwant-discuss-owner(a)kwant-project.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Kwant-discuss digest..."
>
>
> Today's Topics:
>
> 1. Re: About spin orbital coupling (Joseph Weston)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 06 Nov 2014 14:08:24 +0100
> From: Joseph Weston <joseph.weston(a)cea.fr>
> To: kwant-discuss(a)kwant-project.org
> Subject: Re: [Kwant] About spin orbital coupling
> Message-ID: <545B72C8.8060103(a)cea.fr>
> Content-Type: text/plain; charset="iso-8859-1"
>
> On 06/11/14 08:45, ANANT wrote:
> > Hello everyone. I am applying the spin orbit coupling to the honeycomb
> > lattice but there are three different kind of hopping and I am writing
> this
> >
> >
> > sys[lat.shape(shape, (2.46, 0))] =onsite
> > sys[kwant.builder.HoppingKind((0, 0), A,B )]= -t * s_0 - 1j * alpha * s_y
> >
> > sys[kwant.builder.HoppingKind((0,1), A,B )] = -t * s_0 + 1j * alpha * s_x
> >
> > sys[kwant.builder.HoppingKind((-1,1), A,B )] = -t * s_0 + 1j * alpha *
> s_x
> >
> > But this is not right .What should I write in place of this.? please
> help me
> > thank yo u in advance
>
> Hello,
>
> Can you be a bit more specific about what it is that you are doing:
> - what model are you are using for spin orbit?
> - what is the expected output?
> - what is the actual output?
>
> It is always useful to be as specific as possible, especially through
> the medium of email.
>
> Thanks,
>
> Joe
>
>
>
>

Hello everyone. I am applying the spin orbit coupling to the honeycomb
lattice but there are three different kind of hopping and I am writing this
sys[lat.shape(shape, (2.46, 0))] =onsite
sys[kwant.builder.HoppingKind((0, 0), A,B )]= -t * s_0 - 1j * alpha * s_y
sys[kwant.builder.HoppingKind((0,1), A,B )] = -t * s_0 + 1j * alpha * s_x
sys[kwant.builder.HoppingKind((-1,1), A,B )] = -t * s_0 + 1j * alpha * s_x
But this is not right .What should I write in place of this.? please help me
thank yo u in advance